What info do you need? Juvie or adult?
I guess here are the basics:
You need a UTH- hot spot running btwn 85-90 (so you'll need a rheostat, dimmer or thermostat)
One leo will do quite nicely in a 20 L on tile, reptile carpet, or shelf liner.
You need a cool dry hide, a warm dry hide and a warm humid hide. You can create a humid hide by cutting a hole in a tupperware and using a humidity holding substrate. I like using coconut bedding. Mist humid hide daily.
They eat crickets, mealworms, roaches, etc. Dust weekly with calcium with D3.
Whether or not they do better with UVB is quite the debate. If you decide to provide UVB, pick up a reptisun 2.0.
Supply your leo with fresh water.
Leos are curious, habit based little critters! They will get confused, possibly upset if you rearrange their cage often. They're nocturnal, and quite active at night, so providing your leo with plenty of cage furniture to goof off on is definitely a good move! Because of this, make sure you feed in the evening.