The best thing you should do is to find out exactly what kind of turtle you have because turtles' needs vary from one species to another. You must have a water level deep enough for the turtle to swim in peace, so the water should be at least half to 3/4 full. The basking area should be heated with a lamp that has a 40-60W incandescent light bulb for basking purposes. You can buy a platform that is made of heavy duty styrofoam that has a plastic frame and four suction cups that stick this platform to the side of the tank that lowers and rises with the water level. The water should be about 70 to 77 degrees Fahrenheit. You can use rocks that you found outside but you should scrub them to get any bugs or moss off or you can buy them from the store if you want a color variation. You can use regular tap water to fill the tank but if you see any algae growing you will have to shut off the lamp for a day or two until the tank clears up or you can go to the pet store and buy a chemical that kills the algae but won't harm the turtles. If you want to buy plants you can buy real ones but the turtles might eat them, so if you don't want to spend the money to keep replacing the real ones you can buy plastic ones. The best fish you can buy for the turtles is small feeder goldfish that are around 10 to 20 cents each.