Jessica - I hope someone else will chime in here because I'm not an expert - this is my first winter under lights. I have some of those red/blue LED lights myself. The biggest problem is that you don't want to sunburn your plants by just shoving them under light they're not used to. I'd say put them about 12 inches above your plants, starting about 6 hours a day. Gradually increase the amount of time (every 3-5 days). Once they're under lights for about 12 hours a day, then start moving the lights closer to the plants about once a week. Many people here have their lights just 4-5 inches above the plants. My lights are currently about 9-11 inches above my plants and they seem to be doing fine, so I haven't really moved them much closer.

If you search this forum (which is impossible if you're on the app, just letting you know) - you'll find LOTS of posts about growing under lights. You'll even find photos of people's setups.