WonderBoard, Durock, etc. Joints
By using Tile Adhesive and Joint Tape (for the material used.) Kinda like you do w/drywall. You leave a 1/8" gap and go from there.
Here are 2 links to help you with your project:
Super-Tek Tile Info and How To Install Floor Tile
My best to ya and hope this helps.
Jay J -Moderator
PS: You might want to save yourself some 'grief' and buy an early Father's Day Gift (or Christmas Gift or whatever) that tells ya how to install tile. It's mostly found in Kitchen and Bath books.