Welcome Diarmuid.
You will find that people on these boards will be delighted to help where needed so don't be afraid to ask.
Actually the C90EQ is not a bad scope at all. With it you should expect to see quite a lot. On a good night you will see detail on Mars (which is at its best around now), you will ceraintly see detail on Jupiter (low in the southwest after sunset). You will get lovely views of Saturn in a couple of months time.
As far as deep sky objects like galaxies and clusters nebulae etc, that will depend on your location, the darker the better. The nice thing about something like a 90EQ is its easy to toss in the car and go somewhere dark. Join your local club. That way you will end up seeing 100 times more with your scope than you might otherwise.
As nephin says get a better finderscope for the scope, also you might consider upgrading the eyepieces when you get the opportunity.
Most of all have fun.
Dave.
  