present perfet vs simple past 
you have to use present perfet for showing an activity  that you started in the past but it does not finish in the present.
 make the present perfet wiht hava or has plus the verb in past partitipio.
example:
 I have done my homework.
he has seen a beautiful girl.
we have gone to the beach.
you have been singing.


simple past
simple past is to showing  an action or an activity that you made in the past and it is finished in the past.
examples:
she was dancing last night.
the dog ate its food.
they visited la vega yesterday.