3
Mamba beat me to it...
The full 2.5.6 package contains the latest versions of PM, Profile and Protector. You will want to upgrade to the versions included in the 2.5.6 package and no others. Other versions are NOT supported and their quality can not be assured.
Use the methods Mamba already outlined.
What version of Xoops did you upgrade from?
The new versions of these modules should have been copied over the top of your old versions when you did the upgrade and upgrading the modules as Mamba has outlined should work. If you are unsure then I would suggest deleting the PM, Profile and Protector directories from your installation and copying them over from the original 2.5.6 installation package then run update from the admin menu as mamba outlined.
They can be found in the following directories.
modules/pm/
modules/profile/
modules/protector/