Why do you feel the desire to tell someone?
Have you repented of these sins and confessed them to God?
Have all of these activities stopped before you started going to this church, with no relapses, or how long have you been porn/sex free?
Were you in any sort of a relationship while this was going on?
Don't be surprised if there are other people in your church who had a similar past. I did. In fact, over 60% of the men in your average church still look at porn. And that includes 51% of pastors.
If these are things that still tempt you, I suggest an accountability partner. You don't need to give them all the "gory details" but let them know there is sexual sin in your past and it still tempts you (if that is true).
If you just want to confess to someone to get it off your chest, schedule an appointment with the pastor.