Make sure to also look at any slider websites, do a search on yahoo or something like that, that should help. The basics would be
1) at least a 20 gallon tank (or maybe bigger since you have 3)
2) a submersible heater (keep the temp around 80 degrees F)
3) a really good filter (if you get a 20g tank, get a filter that can clean a 60g tank), or clean the tank at least every 2 days
4) a basking area (driftwood, cork bark, etc.)
5) a basking light (any regular light or one specific for basking)
6) a UVB and UVA light (ReptiSun 5.0 or IguanaLight 7.0)
7) clean unchlorinated water
8) aquatic turtle hatchling food if you can find it or reg. aquatic turtle food, although it might be too big for them
-Thats all I can think of right now, but just keep researching!!