Welcome to the forum!
I'm not sure how much you already know, but here's a list of bare necessities:
Filter: Filters gallons/per/hour five times the amount of gallons of water in the tank (20 gallons of water; 100 gph)
Basking platform: The zoo-med turtle dock works the best, but they grow out of it pretty quick. Building an above tank basking area creates support and more swimming room.
Basking Light: For tanks under 50 gallons, you need two lights; a UVB and an incandescent. The UVB (such as the exo terra repti-glo 5.0 26w ($16)) imitates the sun which turns calcium into Vitamin D which fortifies bones and shell. The incandescent (regular house bulb) must keep the basking area at around 88-90 degrees F. For tanks larger than 50 gal, you can use an MVB bulb which is heat and UVB in one. They must be on for 12 hours a day to mimic sunrise and sunset.
Heater: Water temp must stay around 78 degrees for hatchlings and 75 deg. for adults (4+ inches).
Thermometers: One for water, one for basking area. Digital or strips work best.
GRAVEL IS BAD! Anything smaller than their head can and will be eaten. Gravel can get compacted and cause death (as has happened).
Nutrition is too big for me to explain, so here's a list from the main site:
http://redearslider.com/index_nutrition.html
We'll be able to help a little more... helpfully if you can ask specific questions.
Good luck!