Marcus, we recommend keeping the Oxwall software, Oxwall plugins, and Oxwall themes up-to-date. To do this you just need click the Update button in Admin Area.
In case you have made changes in core, theme or plugin files, don't forget that they will be lost after update. So, you need to remember them and apply again or implement the changes via custom plugin.
If your question was about a third party theme, in this case, you will need to contact the theme developer and ask him about compatibility with new Oxwall version.
Just in case, here you can find the steps on how to update you site: http://www.oxwall.org/forum/topic/40793?page=1#post-159389.

Which theme are you using?

If theme designer didn't update it to work with 1.8, then you better move to another theme created by a designer who does some effort to keep his items up to date.

My theme is called "FacebookNext"

I see only 2 HTML files in the theme how hard it is to update?

Marcus, as I said before, you will need to contact the theme developer and ask on how to make your theme compatible with new Oxwall version.

I don't know who that is?

Marcus, you can find this information in the theme.xml file. To do this open ow_themes/yourtheme/theme.xml file in a text editor. 

OK thanks again you rock!

You are welcome :)