As you say, you are a new learner.
For now, use simple past if you are using a specific time, like "yesterday" or "in 2006."
I saw him yesterday. I lived there in 2006.
For now, use the present perfect if it relates directly to right now.
I have worked here FOR three years (and still do) or I have worked here SINCE 2006 (and still do).
How do you know this restaurant is good?
I have eaten here many times. (It relates to right now).
I ate here last week. (It has a specific time.)
Student or Learner