>Hi everybody,
>
>Ok, I have to admit, that I either never done it or did it a long time ago and forgot the basics. I'm trying to create an Invoice document. Actually, I have a template, but it is currently static, e.g. I just type hours and the sum. This sounds stupid to me, so I want to do it right. E.g. I want to be able to type hours I've worked, have Total hours computed and the Total Due computed as well. How should I go about it:
>step by step instructions?
>
>Could somebody please guide me?
>
>Thanks a lot in advance and apologize for this simple question.

I don't remember all the details now; some calculations can be done when you are in a table. Cell references are fixed, and don't adjust automatically, as in Excel.

Another way is to use bookmarks. A bookmark can span a selection, not only an insertion point; and there are formulae ("fields") which can make use of the contents of a bookmark - the actual text that would be selected if you go to the bookmark.