present perfect 

The Present Perfect  Tense is used to express any action that has taken place just now.  This present perfect  tense is also used when the past action has an effect on the present moment. This is called present perfect

Use 1: No time metioning

Actions took place in the place with no definite time

I have already had a lunch break.
He has been to Chile.

Not to use to mention time of yesterday, last week, last month. This is wrong.

I have gone to market yesterday.( WRONG SENTENCE)
We have gone to Peru last year. ( WRONG SENTENCE)

Use 2: Cause and Effect Present Perfect

We also use this tense to when any action has an effect on the present time.

I ate ice cream so I have got cold
I ate dinner So I have got bloated stomach

Use 3: Continuation of action in the present

Some action continues as matter of pride.

She has worked as a music master for over 15 years.
John has attained a lot in his life.

what is present perfect tense

For and Since

Since and For are very natural expressions.

We use For with a period of time, for example:

I have lived here for 20 years.

When talking about a starting point, we use Since, for example:

I have lived here since 1960.

Many do not know exactly how to use this tenses. You use this for a just completed action of today. Do not use this tense for long past. This means do not use for yesterday’s action. You must only use for today’s completed action. Use this tense for long past only when there is cause and effect relationship. Present perfect is the tense where many make mistakes. Usually many do not have enough idea of how this tense looks like. So when you learn this tense make sure to also reason out logically the difference among other tense also.

Finally I tell you to learn tenses by comparing to each other. Only the you can learn better.