Don't panic!!
Firstly, to start a new thread just go to the main home page, decide which topic your thread will belong to and click on that topic.
Top left you will then see 'Start New thread' or something like that... click on that and off you go.
As for the stitch, did you decide to run with music or not?
My gut feeling is that you are over-thinking your breathing and it's therefore not as relaxed as it needs to be.
Just start your run slowly, don't stress about breathing... your body knows what to do and will naturally get the oxygen you need. Pick up your pace very gradually, you'll be fine
