While taking college classes looks good, you're expected to do very well in them if your school thought you were capable of taking them as a high school student. A B isn't bad, but it's not great either. Your school should have explained to you that no matter what you scored in these classes, you must report these grades to future colleges.
Getting into a top school means you need great grades, but the don't need to be perfect grades. You need more than that - you need to find a way to make yourself stand out, hopefully in the field you'll major in. If you're not applying to top schools, than don't worry about it.