How can I use InPrivate Browsing in Microsoft Internet Explorer, to prevent other users of the computer from seeing my browsing history and knowing what websites I've visited?

I just read your information on how to clear search history on a Safari (see how to clear your Safari browser history). It was easy to read and understand. Do you have information on how to clear it on Firefox I have a Macintosh OSX? I can't figure it out.

Is it possible for someone to access sites when i'm online ? Sites have appeared in the history of my mothers computer that i was using but did not access. As you can imagine these weren't particularly desirable sites.It also mentioned about inserting a disk something else i just didn't do. Is it possible to hack somehow whilst i'm online ? at the time i was using google and visiting sites such as myspace and bebo! I would really appreciate your help as it's caused quite an argument but i genuinely did not access these sites.