Some Links for you to practice tenses

http://www.englishgrammarsecrets.com/

I do recommend this page because it has several topics for you to practice. You click on the topic you are interested and you get a short explanation about that subject, and links to some exercises at the end.

http://www.englishpage.com/verbpage/verbtenseintro.html

This is a verb tense tutorial. You have many exercises and at the end you can click on the different examples of the tenses and get explanations of them.

More exercises

Present Simple

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/simcon.htm

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/simcon1.htm

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/simcon2.htm

Past Simple

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/pasted.htm

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/pasted2.htm

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/irpast.htm

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/irpast1.htm

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/irpast2.htm

http://www.englishlearner.com/tests/past_simple_quiz_1.shtml

Present perfect

Past continuous

http://www.englishpage.com/verbpage/verbs3.htm

http://www.englishpage.com/verbpage/verbs4.htm