For a good, comprehensive idea on what and how to take care of your new friend, this page is thorough: http://www.tortoisetrust.org/articles/res.html

You have a red-eared slider if it looks like Leonardo and Michaelangelo. Congratulations!

What Kayann is referring to is that, with any turtle or actually I think any reptile, you should wash your hands before and after handling them. That way you keep any human-illness from getting them, and keep some sicknesses they might carry (Salmonella, I think, is the usual worry from small turtles) from effecting you. Not a big deal - washing your hands before you touch food is always a good idea, anyway!

Does your turtle have a name? What kind of container do you have him in now?