Don't worry about it! Have a good read of this in the beginners section:
http
/www.fishforums.net/index.php?showtopic=88643
You'll need (after you've decided what you want to do):
A tank (go second hand if you can, as big as you want- bigger is easier to look after, and get one with a lid that takes lights)
A filter (a Fluval rated for a bit bigger than your tank will be right)
A light (neon tube type thing, from any fish shop)
A heater (look on the packet for how powerful it needs to be)
An air pump (for bubble curtain rocks that look like long pumice stones)
Substrate (gravel/sand)
Decorations (wood/rocks/divers with bubbles)
And finally, a long way down the road, some fish!
Go to a few fish shops, write down the names of the fish you like. Research them all, and work out what might work (it's unlikely you'll be able to have all the fish you want). Use adult sizes to decide on your stock levels (1 inch of adult fish per gallon is a good starting place but it's not quite that simple).
Then, and only then, formulate an idea start to finish, write it down illustrating what you've learned, and then ask in the beginner section what everyone thinks of your plan.
Good luck- with a bit of reading, a bit of forward planning, and a bit of help, and you'll be fine and have an awesome tank for that money. Have a look in the members pictures forum for some inspiration!