This is a basic Windows 8 tutorial that will show you how to group Startscreen tiles and name the.
Step 1: Go to Start Screen
Step 2: Click on the magnifying glass on the bottom right hand corner.
Step 3: Right click on a tile block
Step 4: Click
Name group in the
Step 5: Enter the name you wish to give for the particular tile group.
Step 6: Click
Name button.
Step 7: Go back to Startscreen and start arranging the tiles according to the groups you have create.

You can only name a group unless there is at least on tile moved to a group. So, if you need to create another group, drag a tile to the right hand side and drop it it will create a new group. Then follow the steps from step to to name the group.
source:windows8hacks