The layout of CDG2 goes something like:

2B - 2D - - - 2F
- P - P - RER - P
2A - 2C - - - 2E

You can get a shuttle, or you can walk it, depending on how energeting you're feeling. Just follow the signs for 2C, then the station - it'll take about 10-15 minutes.

2B, well, same advice in reverse.