
Unfortunately you've learned that all paper-training does is teach a pup that it's acceptable to mess indoors. :(
The best thing to do is take up
all the paper and go right back to basics, treating him like an 8-week old puppy. Take him outside to the garden every time you think he might need to toilet and stay with him until he performs. When he starts to 'go', give him the keyword you want to use ('busy', 'hurry up', 'be clean' or whatever), then give him lots of praise when he's finished. It'll take a while to retrain him, but if you're consistent you'll get there. Good luck!
:)