There is a good reference online at msdn in the topic Redesigning Classic Reports with Visual Studio Report Designer you should also consider looking at Designing Reports for the RoleTailored Client which has several walkthrough guides for creating different report types.
You can use automated tool for converting Dynamcis NAV Classic reports to RDLC - simplanova.com/.../
Rene Gayer's book has a good section on report transformation. You should buy that and read it. Here is my review www.teachmenav.com/.../book-review-microsoft-dynamics-nav-2009-inside.aspx