wow!!!!! a 6 foot tank, that's absolutely awesome, I'd love one that size!
As other's have said the first thing is to be clear from the outset what you want from it. Go looking for inspiration from the members pics section, or just do a google image search on fishtanks..... when you've found some that you like post them for us and we can give you some more precise advise on what sort of equipment, expense, maintenance your looking at to get that. You really have a huge amount of scope for what to do with that sort of tank.
There's loads of pinned topics in the beginners section about cycling and starting out, just read as much as you can and you'll soon get the hang of it.
In the Tropical Chit Chat forum there's a pinned topic with reviews of fish stores all over the UK and USA, have a browse of there and hopefully you can find some decent shops near to you which you can visit, getting to know the staff and get an idea of prices is always a good idea when starting out.
Also these are my first (well probably only) two rules every beginner should learn
1 - Don't believe everything they tell you in the fish shop...... remember they want your money, sadly there are some very unscrupulous fish shop staff around who will quite happily sell you anything regardless of if it's suitable for you or not.
2 - Do your research, it's a really bad idea to just go into a shop and see a pretty fish and buy it, I think a lot of people have done it, I know I have before, and I've ended up with fish that will eat other's in the tank or will grow so big I need to re-home them. If you see something you really like, go home, look it up and if it's suitable then go back and buy it. You just have to remember if you buy a living animal you take on the responsibility to give it a safe and happy home, well you can't do that if you don't know what it's home should be. So do your research before you buy.
and lasltly..... good luck, and have fun, I wish I had a tank that big to play with, your very lucky!!
Enjoy and let us know how your getting on