Welcome to the Game!
You're in for a TON of fun!!
I agree with jebbo - start off with a box of the Warriors of Minas Tirith. This will give you 8 models with swords and shields, 8 models with spears and 8 models with bows. Also, they are plastic - so it'll be a cheap way to get started!
As for paints:
MUST HAVES:
Dwarf Flesh
Scorched Brown
Boltgun Metal
Chaos Black
Bleached Bone
NICE FOR HIGHLIGHTS AND OTHER STUFF:
Elf Flesh
Bestial Brown
Mithril Silver
Flesh Wash
Snakebite Leather
Shining Gold
Dark Flesh
Shadow Grey
Codex Grey
There are quite a few painting guides for Gondor all over the place - and plenty of pictures up here on the site of ppl doing the warriors. Good luck with your painting ~ and just remember to take your time and ENJOY yourself!
Once you get that done, I'd consider going for some Knights of Minas Tirith or Rangers of Gondor! (and they pocketbook will get thinner - and your fun will grow! LOL)