Past tenses

Watch these for the distinction between past simple and present perfect:

Or read this:

http://www.englishgrammarsecrets.com/presentperfectorpastsimple/menu.php

Do these exercises:

http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/ppvpast.htm 
http://www.perfect-english-grammar.com/past-simple-present-perfect-3.html 
http://www.englishgrammarsecrets.com/presentperfectorpastsimple/menu.php

For repeated actions in the past, use "used to":

http://www.englishgrammarsecrets.com/usedto/menu.php

Then, read about the distinction with past perfect:

http://esl.fis.edu/grammar/rules/pastperf.htm

And do these exercises:

http://www.englishgrammarsecrets.com/pastperfect/menu.php

http://www.englishgrammarsecrets.com/pastreview1/menu.php

http://www.englishgrammarsecrets.com/pastreview2/menu.php