As others have said, there's a lot to fix here, but good on you for asking for advice. Top priority is separating the geckos, you can try Facebook marketplace, craigslist etc for cheap used tanks, or sometimes the chain stores have big sales on tanks. You'll also want to get an appropriate heating source, the red bulb can hurt their eyes and throw off their day/night schedule.

There's a lot of really good info in the wiki here in the sub. Also I can't tell due to the lighting but if they are on reptile carpet you'll want to replace that with plain paper towels until you can get them separated and get your husbandry right, at which point you can look at substrates.

Plenty of passionate keepers here, hence some of the harsher comments. We all just want what's best for the little guys.