could you explain how to use perfect infinitive correctly in eng language

Answer 1

http://grammar.ccc.commnet.edu/grammar/verbs.htm#infinitive

There's a chart here with basic explanations of different infinitive and gerund forms. Remember that perfect forms use 'have' for the most part :

to have run (the race)
to have taken part in the performance

to + have + [verb form]

This can also be passive: 'to have been chosen'

Be sure to read through other sections, especially the one with the blue button below this.