I have figured it out. It is really easy - all you have to do is use the built in html editor and click the formatting button to allow you to enter HTML manually. I have now updated all my main categories and the home page with h1 headers as the bolded part of all intro descriptions on the top of each page.
You shouldn't really do that.
For best results, the only thing you should have as H1 on your site is your sites name, and that should be the first thing on your site.
Usually it's used in combination with clickable logo image that replaces text in your H1 tag.
There's lot of info on the subject all over the net, you can read this for starters if you want to implement it the right way.