If you want to process the tracks the same (i.e. add reverb):
1) select the tracks you want
2) hold down ctrl
3) right click on one of the selected tracks
4) in the context menu select "Insert Send"->"Insert Send Assistant"
5) Click the "New Bus"
6) Set the output to your master bus
7) Set the bus name
8) Click "Choose Effect", for each effect you want to add
9) set the checkboxes to taste
10) Click Ok
If you want to process each track separately, you will need to add the effects to each track individually.