Go through the present perfect explanation sheet to introduce the situations in which we use this form. It's useful to emphasis that we cannot use the present perfect tense with specific time expressions, for example 'Yesterday I have eaten lunch' is incorrect.
This worksheet tries to demonstrate that the present perfect tense can be useful when stating something that has happened in the past that has a significance in the present moment (and the time it happened is not important, just that did or didn't happen).
Remind the students of the way to form the present perfect:
subject + have/has + past participle.
Have them complete the worksheet and check the answers together.