With our boxer he was crate trained during the day and nights they will not go where they sleep. During the day he was limited to how much of the house he had access to, we used baby gates to block areas off. You can buy pads to go on the floor for pups its the same type of material we use in the hospital on patients beds for a leakage. We put that down and kept putting him on the pads when he looked like he wanted to tinkle.
We noticed that when he would start sneefing around and started turning in ciricles it was the sign I want to go. Took about 2 months to get him trained. Now he goes and sits by the door if he wants out, hope this helps I know its not easy potty training them but its well worth it in the end.