Halo 4 Legendary Campaign Help?

I want the commendation for completing the campaign on legendary. My friends said they would help but there never online. I’m on the mission infinity on the last check point. can anyone help me complete the rest of the campaign on legendary please? i am not saying right this second. but whenever i am on and i need people’s help to finish it i need to people to contact and to help me.

I haven’t played campaign yet, is it any good?

will not let me complete the campaign because its marking me on the Legendary progress and i am stuck on the 4th mission (i think) called infinity. from what i have played i think it is good.