Download the full version of 6.05 from the UBB Member Area. There is a link at the upper right of this page. There are full instructions in the zip file and there are instructions in the UBB News announcement that you can read by clicking here

Note: Be sure you do not upload the new files starting with vars_ as that will overwrite your configuration. You do need to upload the vars_wordlets_ files, however.

The current version is 6.05