Okay then.
It will be difficult to book any wedding even for very little money without some sort of wedding portfolio, not impossible but difficult. I have seen people struggle to get weddings even when they are offering to work for free.
Your best option would be try and get some second shooting gigs. This will allow you too to get the experience of working at a wedding, see how everything works and hopefully get some cash or images for your portfolio. Most photographers that use a second will give the second the option of either working for free and being able to use to some of the images or getting paid, usually not both. If you go the route of working for free so that you can use some of the images for advertising bear in mind you might not be allowed to use them for several months or at least until after the couple has received the photos. Quite a few will ask you to wait until 6 months after the couple have received them, but not all.
I have seen lots of posts on here over the years saying how difficult it is to get second shooting gigs but to be honest that is nonsense, it is very easy to get second gigs if you go about it the right way. Firstly, don't reach out to local photographers in your area by email, complete waste of time. I get 5/6 emails like that every month and they go straight in the bin once I realise what they are. Someone who is actually a member here emailed me looking to second shoot a while back.
Not sure if they realised who I was on here or not.
You need to try and make friends with a few wedding photographers, so you need to hang out where they do. The easiest way to do that will be to attend a few wedding photography workshops. Seek out the guys and girls who are full time, show a genuine interest in what they do, get as much info on how they do things as you can look them up online etc. Don't mention during the workshop that you are looking to second shoot. Once you have all the info you need phone them, don't contact by email, social media etc. Just ring them and say Hi, I met you at such and such workshop, love your work blah, blah, blah, looking to get some experience, happy to come without a camera and hold bags etc for a couple of wedding if you let me shoot later on. Whatever it takes really. Better to pick those whose style you actually like. Also better to do this with photographers who aren't in your local area and won't see you as competition. Once you have some images you can use join the thousands of second shooter groups on Facebook post in each of them with images explaining you want more second gigs. Reply to all the wanted ads on there looking for seconds. Don't bother with those until you have some wedding images first you will be wasting your time.
Once you have say 10 weddings under your belt that you can use images from set up a website and social media etc. At that point if you are cheap enough you should at least be able to book a few weddings yourself quite easily enough to give you a little spare cash anyway. Don't use images taken at workshops, that is just a s*** show.
If you want to actually have a proper business though the approach from then on is very different.
You may want to have a think about what your expectations of shooting a wedding are. Shooting very cheap or free weddings 99 times in 100 is going to be a complete waste of time for building a portfolio and will lack any sort of creativity. Cheap weddings, will be in crap venues, with couples who don't value photography. You will get very little creative engagement from those sort of weddings. Those type of weddings will involve working all day for couples who treat you like crap and are very demanding in terms of making you do what they want rather than giving you the freedom to do what you want to do. You only get that freedom from couples when you are able to prove what you are capable of from your portfolio. More expensive weddings will be at much better venues, with couples who aren't booking you just because they feel they have to have a wedding photographer. I have done really cheap weddings and the vast majority of the day in every case has been taken up shooting endless amounts of awful group photos. Thank God I don't have to do that crap any more.
Be prepared to hate images shot as a second later on though, once I started shooting my own weddings and developed my own way of doing things I deleted all of those images from weddings I had seconded from my website and social media as they really didn't fit with the way I like to do things. Cringe even think about them now.
I fell into weddings by accident I had no intention of shooting them. Everything even just that
@F/1.4 told me about them put me off completely. Many years ago I helped a guy I know with a glamour photography workshop. At the workshop I got friendly with a wedding photographer who was based over 50 miles from where I am. She worked with her husband at the time. During the workshop she asked me if she could come to some glamour/fashion shoots which is what I was mainly shooting at the time, that actually never happened but when her husband was struggling to get time off work for a wedding she had a few weeks later she got in touch with me. I then shot some weddings with her, I wasn't allowed to use the images because she paid me for the first few. After that when she had nicer venues and couples I shot a couple for free so I could use the images. Over a 3/4 month period I shot about 25 weddings for her in total and had images from 10 weddings to set up my own website etc. as eventually once she learned to trust me she allowed me to use images as well as paying me.
If I was starting now I would do things very differently but that is because I would be coming at it form a business point of view rather than than just dipping my toes as I did then. No point going into how to do that though if you are just looking to earn some beer tokens to supplement your income.