I am going to assume you are trying to do this in a word processor. Since...

I am going to assume you are trying to do this in a word processor. Since Linux Mint ships with OO, my guess is you are trying to use Open Office Writer. Your best bet, in that case would probably be to pose the question to the Open Office community, if it's not answered in the Open Office documentation at http://support.openoffice.org/

If you are using AbiWord, which may have been installed along with Gnome, you should be able to find help here: http://www.abisource.com/support/manual/

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