When we first got our boy boxer he was a gem!! I dont even remember having any accidents in the house. It was like he knew what to do all along..
Fast forward a year...we got our second boxer, a girl, and holy cow it was a *nightmare*
It seemed like she had absolutely no concept of peeing on the grass opposed to peeing on carpet. Every chance she got she was going inside. #1 and #2. I came to the forum desperate for help and the best advice I received was "it will get better!!" It felt like months of accidents when in fact it was only about a week and a half. We even had egg timers going off every 15 minutes so we could go outside, and try again!
Some other great advice I received was:
-(like mentioned above) Never scold,yell, or run at them when they have an accident. Just pick her up and take her outside. Obviously they just pee'd so that wont happen, but it gets the association with peeing and being outside...
-when she does go outside and go potty, have your treats with you and give them to her as soon as she's done squating, and of course, lots and LOTS of praise.
- If she seems to be having a set back with the accidents, attach her lead and clip it to you. That way she will be right next to you at all times and you can at least know where she would be having an accident if it did happen. (When I used this technique, she never had any accidents while cliped to me. I thought that was interesting)
Sorry this is so long! I have just gone through all of this too, so it hit home. Ha!