We use Present Perfect to:

 - talk about an action whose effect is noticed now, often with "already, just, yet".

 - talk about how long has something been going on, often with "for, since"

 - a life experience you have or haven't had, often with "ever, never, before"



Watch the video to get familiar with the use of  Present Perfect





Then click on the link below to do some grammar work

Source: British Council Learning English