An explanation on how to use for and since.
http://www.englishexercises.org/makeagame/viewgame.asp?id=1394
Complete these exercises, print them and paste them on your notebook.
http://www.eclecticenglish.com/grammar/PresentPerfect1D.html
http://www.ego4u.com/en/cram-up/vocabulary/since-for