Simple past :

To form the simple past tense of some regular verbs that end in a vowel+consonant,double the consonant and then add  -ed  .

   hop   + p  +  ed  =hopped.

To form the simple past tense of most regular verbs, add  -d  or  -ed .

 decide  +  d  =decided.

To form the simple past tense of verbs that end in a consonant + y ,change the  y  to i and then add  -ed .

   try  +  i  + ed  = tried.

   cry  +  i  + ed  = cried.

 NOTE:

Many verbs in English do not form the simple past tense by adding -d  or -ed .

They are irregular, so you must just memorize some of them. 

         good luck!!