The simple past: regular forms.

When you form the regular past tense in English you need to pay attention to two things: pronunciation and spelling.
PRONUNCIATION
To form the simple past you simply add -ed to the end of the infinitive and you have the simple past.
-ed can be pronounced in three different ways: /t/, /d/ and /id/.
“T” is a voiceless consonant what we called “sorda” in Spanish that means you will feel no vibration in your throat, just a short explosion of air as you pronounce. These are some voiceless consonants : p, t, k, s, sh, ch, th (as in thing)
“D” is a voiced consonant what we called “sonora” in Spanish that means you feel a vibration in your throat when you pronounce it. These are some voiced consonants : b, d, th (as in then), v, l, r, z, j (as in Jane)
Vowels are always voiced.
If a verb ends in t or d then the -ed will be pronounced as a whole new syllable /id/
So the sound of the past : -ed will assimilate the sound of the preceding sound and so if it is a voiced sound the pronunciation of -ed will be voiced /d/ and if voiceless it will go to /t/.
To sum up, you have three options with the pronunciation of the regular past tense -ed: /t/, /d/ or /id/
Here you have a video to practise
and some interactive exercises:
Choose the right sound
Try again
Number 3
Nice one from the BBC
SPELLING
With most regular verbs, the simple past is created simply by adding -ed. However, with some verbs, you need to add -d or change the ending. Here are the rules:

Verb ending in…	How to make the simple past	Examples
e	Add -D	live lived date dated
Consonant +y	Change y to i, then add -ED	try tried cry cried
One vowel + one consonant (but NOT w or y)	Double the consonant, then add -ED	tap tapped commit committed
anything else including w	Add -ED	boil boiled fill filled hand handed show showed