Present Perfect
Use present perfect for events that started in the past and continue to now.
We often use for or since.
for = How long?
I have lived here for 5 years.
We have studied English for 6 months.
He has had a cold for a day.
since = When did it start?
I have lived here since 2004.
We have studied English since September.
He has had a cold since Tuesday.
Choose for or since.
Use simple past or present perfect.
If the event began and ended in the past, use simple past.
If the event began in the past and continues to now, use present perfect.
Be careful with have / has.