is 2.75 miles in 21 minutes 31 seconds a good time for someone reasonable new to runnig to be getting?
will i just improve by keep runnig, and increasing speed, etc? i found that taking deep breaths, and holding for a few seconds before runnig decreases the chances of getting a stitch, has anyone else tried this, or know why it works? is it because it stretches the diaphragm?

That's about 7:49 minutes per mile, pretty decent for someone fairly new

Yup, basically Try not to increase too much too quickly, though, speed or distance, as you run a fairly high risk of injury that way. Keep it gradual, and your improvement will be surprisingly fast

There are loads of ways to fix stitches, that's one good one As far as I know, no-one's figured out exactly how we get them or how to make them go away yet...