Question

What is the difference between past tense and past participle? what is used when?

for example
past tense: I walked to the Cafe.
past participle: I had walked to the cafe.

Answer 1

Regular verbs have 4 principal parts. I'll list them for you:

Present - walk
Simple past - walked
Past participle - walked
Present participle - walking

Notice that the simple past and the past participle are spelled alike in this particular verb. The simple past form is to be used alone, no helping verbs. The participle needs an auxiliary (helping) verb with it to make it serve as a sentence's main verb.

It's easier to see the differences with irregular verbs. Here's one:
Present - ring
Simple past - rang
Past participle - rung
Present participle - ringing

Do you see the difference? Can you do the same with other verbs?

Answer 2

Thank you for your nice explanation, My another question in this connection is, is there a difference in meaning between these past tense and past participle sentenses, I hope I wrote these sentenses correctly.

I rang the bell
I had rung the bell

Answer 3

Your sentences are correct.

"I rang the bell" is a simple statement about what you did in the past.

"I had rung the bell" implies that you did this action before something else.

Example:

I had rung the bell before I realized no one was home.

Answer 4

Thank you very much.