Faire causatif; causative constructions with faire
When one does not perform an action oneself, but instead causes the action to be performed, the causative construction is used. It is formed with faire + infinitive, sometimes followed by à or par to indicate the agent. The tense of the verb faire sets the tense for the construction, and the past participle is invariable:
Nous ferons ériger un monument sur ce site. (We'll have a monument erected on this site.)
Je me suis fait couper les cheveux. (I got my hair cut.)
Le professeur a fait écrire un essai à (par) ses étudiants. (The professor had his students write an essay.)
Note that object pronouns precede the verb faire. If the agent is rendered as a pronoun, the indirect object pronouns are used.
Je le lui ai fait faire. (I had him do it.)