The upgrade process is similar to the installation process, with the exception of a few steps that do not need to be carried out again.
Before doing anything else:
Make a backup of your entire dmBridge installation (located, by default, in the /dm folder relative to your web server's document root).
Also make a backup of your supplementary dmBridge data (located, by default, in /dm/data, but hopefully no longer located there because you moved it someplace safer).
Finally, if you are storing social data in an external database (such as MySQL), make a backup of the database.
Next, begin the upgrade process:
Move your old dmBridge folder (by default, "/dm") out of the way.
Unzip the dmbridge-x.x.x.zip distribution.
Move the resulting dmbridge-x.x.x folder to the location of your previous "/dm" folder.
Go through the Installation section, skipping any steps that only needed to be completed once.