Cycling the "tank" is about setting up the environment/water chemistry for your fish.. Ammonia produced by fish waste and other sources is harmful to fish, and needs 'friendly' bacteria to break it down for you. This is all part of the nitrogen cycle....
http/www.fishforums.net/index.php?showtopic=113861 is a good place to read up on cycling the tank.. this is about fishless cycling, which is the prefered method for most people on this forum. It avoids any stress on fish by adding 'hardy' fish into the tank to start the cycle. A fishless cycle is about manually introducing ammonia into the tank to perform the cycle, which involves testing the tank frequently to see how it is cycling and when to add more ammonia. once the tank can cycle 3-4 parts per million of ammonia within 12 hours, you can add your fish.. more fish in one go than you could if you were using fish to cycle the tank..
So.. a list of things you need.
1. time to read some of the pinned topics in on this forum (time has been one of the biggest things i needed to set up a tropical FW tank)
i.e. at the top of this part of the forum.
2. if that is just an air pump, then you will need a filter
3. Heater
4. a good test kit, if you dont already have one ( i presume u already use dechlorinator for the water)
5. read up on compatibility of different fish.. there is a fish index on this forum
6. decide on whether you would like reall plants or not, this may affect your choice of fish, substrate and the need for plant food in the substrate, such as 'first layer laterite'
7. decor to suit your tank and fishes needs
8. fish net (if you dont have one)
9. gravel/sand vac / syphon for weekly water changes (if you dont have one)
Im sure there is more that will come to me. The main thing is to research the fish you want and their compatibility with each other.. This foruim is a good place for that.. many a member has been miss-led by their local fish shop.
i started a checklist when i was setting mine up..
here...
http/www.fishforums.net/index.php?showtopic=117462&st=0
Good Luck
Cheers
Squid