Lair of the Asp

Contol + A, To select all. S, to split the tracks. F5, to select the Smart Tool, if you aren't already using it. Grab the edge of one side of where the split is, so that it has the arrows pointing both ways and drag it to delete what you don't want with the grid snap enabled. The select the parts on the right side, holding down the tab key will let you select more than one track at a time if needed. Using the smart tool cursor, make sure it is in the upper part of one of the tracks and now looks like arrows pointing in all 4 directions, and drag the data to the left closing up the hole.

If you want to add a section or time to a song or project that you are already working on. Put your cursor where you want it to happen. Go to the project drop down menu and select under time/measures, add as much as you you want to add, hit OK and you have a split in your tracks and the track data to the right of the cursor will have moved over leaving a blank spot in all of your tracks.