Read the rule

Present Perfect with since and for

We use Present Perfect with since or for to talk about situations that started in the past and are still continuing now.
I've been at this school since 2009. (= I started at this school in 2009. I am still at the school now.)
We've lived here for three months. (= We arrived three months ago. We still live here now.)

For + periods of time: three years, two days, twenty minutes, a long time.

Since + starting time in the past: yesterday, July, 2006, last year, 12 years old.

We do not use Present Simple in these cases:

We live here for three years.

I am at this school since 2006.

We use "How long...?" to ask questions about situations that started in the past and are still continuing now.
'How long has she worked there?' 'For three years.'
'How long have you known him?' 'Since I was five.'