Passing paramter from the sidebar to page call

Hello there, :o)

I have a mini webcalendar in my sidebar and in the content area there should be a singleday/month view.

On Click of one of the days of the mincalendar I’d like to open page_id=3 (where the function builtwebcalendaroutput($year,$month,$day) is called) and I have to pass some parameter like &year=2008&month=7&day=7.

Is there any function from which I get all the passed parameters from the url?
And btw, is it generally possible to call such a function and use those paramters to get the output?

I’m really new to this wordpress thing :o)
AND if anybody knows a good page or book for learning how to handle this software – pls tell :o)

greetings, mathew