Hi and welcome!
@PoseidonTheChameleon is giving you great info.

I just want to make sure you buy the correct uvb light. You’ll need a T5HO fixture with a 5.0 or 6% uvb bulb. These are the long tube lights. As you’ll eventually need a much larger enclosure for your little cutie, it would be more economical to buy a 24” long uvb. One such as this is perfect.
https://www.pangeareptile.com/store/arcadia-prot5-uvb-kit.html It costs a bit more than ReptiSun, but is not only a great brand, but the bulb lasts a year, which is twice as long as Reptisun. Before you add a 100w basking bulb, you temps shouldn’t exceed 80 at basking level. Humidity of 44% is perfect. You don’t want that to go any higher than 50% during the day time.
There’s several resources that I’d recommend you check out, which will help guide you in caring for your little guy.
https://chameleonacademy.com/chameleon-basics/ https://caskabove.com/ and on YouTube check out Neptune the chameleon. Of course the forum is full of members who have started where you are and enjoy helping new keepers get everything just right.