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

  -It includes general information about the affirmative form of the simple past tense

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

  -It includes general information about the negative form of the simple past tense

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

   -  It includes general information about the question  form of the simple past tense

         http://www.englishpage.com/irregularverbs/irregularverbs.html

-  It includes general information about the regular and irregular verbs

       http://www.learnenglish.de/grammar/tensesimpast.htm

-  It includes general information about the use of the simple past tense

       http://www.eslgold.com/grammar/simple_past.html

        http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/pastnq1.htm  

-  It includes exercises about the simple past tense