Well done Phoenix, for asking for help before going shopping!
The best 'starter' puffer in my opinion would be two or three dwarf puffers, they're hardier than most and reasonably undemanding, but they still have the same amount of charm and cheekyness as the bigger species! Also they're true freshwater, so no worries about getting the salt right like with greenspots or figure eights.
Puffers need more room than other fish as they are terretorial and are messy eaters, so the tank would need to me at least 15 gallons for three dwarf puffers.
You can read about cycling in the beginners section.
The tank needs hiding places (terrecotta pots are ideal) and real or fake plants to break up the puffer's line of sight. Sand on the bottom is best, as sometimes they like to bury themselves, and uneaten food is easy to see and remove.
Food is anything small & meaty such as bloodworm (live is best or frozen), brineshrimp (seamonkeys) and small ramshorn snails, however, with puffers the size of the food does not deter them and they will kill and eat large apple snails and even big shrimp like bamboo or mountain shrimp several times their size.
They can be kept with small catfish such as bristlenose plecs or ottos, but not with 'free swimming' fish like guppies, cories or tetras.
That's a Dwarf Puffer in my signature (on the left, duh)
