Thanks for the responses! Sorry I really have no idea on these things, being completely new to the sport.

So trimming is basically slightly shifting the front gears but not too far so that it actually shifts?

I rode 20 today and was trying out different gears going up and down hills, should I shift down/easier (does down mean easier?) before approaching the hill and shift up as I go up? I seem to find that doesnt kill the gear system.