Journal entries when you update your InsaneJournal may be changed using HTML. If you do not know how to use HTML, you may search for an HTML tutorial over the internet.
Please note that when you are done using these tags they must be closed. This is done by putting </(tag here)> at the end of the font you've wished to change. For instance, <b> would be closed with </b>, otherwise it would make the rest of your entry bold.
However, InsaneJournal now allows you to easily customize the text in your entry with the Rich Text Update [http://www.insanejournal.com/update.bml?mode=full&rich=1]. You can add special effects to your text in the similar way that a word processor works.