Rough Night

[missjean]

I was wondering about the number of flats too, but Trek420 & Muirenn covered that pretty well.
The whole switching gear thing gets better with practice. Before you put more money into your bike, take it to a well respected bike shop and ask if there is a mechanical reason you are having trouble with shifting, ie: worn chain & rings, gunked up cables & housing, etc.
If that's not what is causing the shifting problem, try to take some time and find a safe place to ride, best with some hills, and don't worry about anything (speed, distance) except practicing shifting - going up hill, down hill, fast, slow, stopping, starting. You'll get it soon enough!