One of the things that you might have noticed is that as you practice more and more, you have been able to hit higher notes on your trumpet. From the highest note that you can hit to the lowest note you can hit is called your range. Many of the pieces that you will begin to play now will require you to hit notes that are at the top of your range. Some notes you might not be able to hit. This is where practice comes into play. If you have a daily practice schedule in which you practice for at least 30 minutes, you are in good shape. If you can't hit high notes at first, don't tear your lips to shreds trying to hit them. A really bad habit that most players get into is jamming the horns into their face trying to hit high notes. This is called the All Pressure Method and you should try to avoid it at all costs! There is no such thing as no pressure playing, but too much pressure can damage your lips to the effect that you can't play high for a few days.
If you can't hit a note that is in the upper part of your range after about the third time, don't push it. Lay off and try to hit it the next day.