As you confess to being a "non-expert" the solution may be quite simple. (hopefully!)
There is no problem in this respect, with Microsoft OS, but as to where you are trying to save. For example, the old "Documents and Settings" Folder is now off limits, for various good reasons. See if you can save to a known, open folder on your computer. For the experiment, create a folder and name it "MyDocs", (for example) and see if you can "save as" to there.
Whichever way it goes, post back and I or someone else can alaborate on the problem you are having.