Experiment
Start with a Teddy Bear. Something that isn't going to complain or move.
If you're using a white background, you'll need to light that, so thats one of your lights used. You can shoot "at the background" to reflect or "through the background" from the back.
You can use your reflector to bounce some of the light back onto the subject, though silver side produces harsh light, gold is harsh but warms up whatever the light is hitting.
You can use the white-
Your biggest issues will be hotpots or light fall-off. Your aim will be to light it as evenly as possible. Sometimes 2 lights for the backdrop is necessary, depending on how many people you are packing into a portrait shot.
If you intend to use black backdrops for low-key portraits, you can use your two lights more creatively rather than one being used to power up a backdrop.
There are many youtube tutorials you can find, for free that will be most informative.
F7 is a good starting point for getting things in focus (i'd say upto 3 people, if you can get them in a line, great, gets more difficult when you have "layers" of people - you may have to increase your F-stop to capture more people in focus.
Also, google "Lighting setup examples", you'll find some useful stuff that way too
Experiment experiment experiment.!