Ago and Before: Are they same?

How do you use ‘ago’ and ‘before’ in a sentence ?

Ago is used with a past tense and a time to count back from the present.

Example : She died three years ago. Dad left ten minutes ago.

Before is usually used with a past perfect tense.

It can also be used to mean ‘at any time before now / then’. It can be used with both present and past perfect tenses.

Example: I had seen this movie before.

I have felt this before.

I had reached there before he arrived. So, you can say , I joined SHEROES 2 days ago but my friend had already joined before I knew about the app.

Can you write some more examples ?