First of all you talk to the monk next to the gate of war at home.
He will give you a list of items that you got to bring for him to get the Ancient Curses.
The items are
5x Pharao's sceptre = Pyramid plunder minigame the higher thieving level you have the more chance of getting a pharao's sceptre
100x Dragonbones = monster tele Taverly dungeon squeeze through the pipe and kill the blue dragons
10x Runite ores = you can get them by thieving General stores stall or you can mine them
Torag's helmet= You can get it from players or barrows it is a very rare item soo be prepared to pay shitloads of money...
25million gp = well thats not hard or easily to get you can thieve them or kill monsters like frost drags they usually drop 500k.
100 Torstol seeds = they cost 11000 each and if you are going to buy 100 of them you need 1.1m
When you get all these items simply talk to him and he will take them and you have unlocked the Ancient Curses you can change the prayers by talking to him again...
Hope this helps you guys.