For = Duration of the event  the period
Since = The starting point of the event
1  If you since came up with a single act we put it in the time of the present perfect:
Ex:
She has learned English since 1995.
2  If you since came up with They did put before the present tense and then full time the past simple.
USE :
The present perfect + since + past simlp
Ex:
She has been in bed since she arrived home.
He has been studying since he returned from
school .
Note the following table:
Since

For

Since 8 o'clock
Since 2003
yesterday
Since last night
Since April
Since Friday
Since then,
Since spring
Since his
arrival

For 2 hours
For 5 years
For a day
For a
night
For 2
months
For 4 days
For ages
For a
season

1 If asked to use to put since instead of when
We use the present perfect time exile:
Ex:
I last saw her when she was a child.
I haven't seen her since she was a child.
2 If asked to use to put Ago instead of For
We use Began to Before the source of the
original act:
Ex:
She has played tennis for five years.
She began to play tennis five years ago.
3 If asked to use to put Just instead of a
a moment ago
We use The Present Perfect
Ex:
She left home a moment ago.
She has just left home
4 If asked to use to put Since instead of For
We follow the method as follows:
He has worked as a teacher for 9 years.
He has worked as a teacher since 2005.
Its 9 years since he worked as a teacher.
5 We use for instead of since
Ex:
The last time I met her was 7 months ago
I haven't seen her for 7 months