Ok first you would need a tank, assuming you dont already have one. You can use a 10 gallon for a baby but I recomend upgradd it or just go ahead and get, say, a 20 gallon long. The reason behind this is a 10 gallon is very small and although a leo can live in it they wont get as much exercise and possible be as happy as they could be in a larger tank.
Now you need a UTH and I also recomend using a termostat, but you dont have to. The termostat pluges into the UTH ad keeps it at a constant temperture that you set. Leos dont need any UV so no lighting is nessasary. You will need a hide box for both sides of the tank, so he can be warmer or cooler, and also a humid hidebox. If needed on of the side boxes can be the humid hide. I make my humid hides out of cool whip containers with peat moss as the substrate, keep these moist. You will also need a water dish and a calcium dish. As for substrate I use paper towels, but if want more natureal slate or tiles are fine. I highly recomend not going for any loose substrate as leos can get impacted on them.
Now for the feeding part you will need some vitamins and also some calcium. I use Herptivie and miner-al but you can get Reptocal.
I think this is all the vital stuff. Have fun! :-]