if you can resize your photo's to ensure that they're no larger than 1024 pixels on the longest side, and no larger than 350kb (as far as as I remember - there has been some talk of changing those parameters, but I'm pretty sure that the above is a "failsafe" combination) then you can actually just use the "upload" button that's below the "entry box" that you type new comments into.
Simply click on the button, and it'll open a "upload dialogue" on your computer where you can select the file you want to display, and it'll "upload" - you then tell the computer to display it as either a thumbnail, or (preferably) full size and you should be good to go.
Personally, however, I would suggest signing up for a free account with Flickr, even if you don't use it for anything other than hosting pictures (i.e. ignoring all the "likes" and so for) it's 1Tb of web based backup for your photos...