Gadolig struggling with porn but finally learning to deflect it here; pray, read good Catholic books, stay away from the internet if you are tempted to watch porn, go to the gym to tire yourself out so you go home, take a shower, eat dinner and fall asleep quickly. It's gonna take time, and the first weeks are the hardest; I lasted three months, then I slipped and despaired, thus went into the usual vicious circle. Now I am slowly crawling out with God's help.
Prayer is key, together with going to mass, receiving the sacraments of reconciliation and communion…say the rosary every day, take an hour of your day to stay in silence and pray the five mysteries of the day. And if you can, start to slowly use our phone/laptop/computer less and less, acquaint yourself with silence and fill your time by doing house chores, reading and/or doing something useful in and for your local church and parish.
Pull the plug from Facebook, that damned sinkhole and pretty much the antechamber to madness, self-centered opinions and self-loathing for the sake of attention.
I am 28, it took me 27 years to start to understand how important prayer is in this fight, and how weak I am no matter what if I do not put myself into God's hands.
Take care, and let's pray for one another :)