Wow, err...
There's one essential thing about working with paint.
COPY AND PASTE!!!!! So that your windows don't breath, everything doesn't move out of place, and so that you won't get screamed at by more experienced people. This is one of those typical beginner comics. Might want to make text bubbles, make the floor lighter and of a custom color, (Default colors=bad) shade, (But then that's something you learn later on) and overhaul this comic. I mean, all beginners think their comic is good. (Well most of them.) So when they hear comments like this then they get angry. Don't get angry, you need to improve, really though. Ask one experienced comic creator about what's most improtant with your backgrounds and characters, and they will say copy and paste.
copy and paste, (Please)
Sahaqiel