How do i get into a MW2 infecton lobby?

Ive wanting to get into a mw2 infection lobby for xbox ever since i herd about em. So, ive been looking on youtube and ive been msging ppl but still i nvr get an invite. is there like a bot tht i like msg or somethng n it auto invites me? Or if u host thm personally just leave ur gamertag in the answer. Thsnk You!!!!