I've got my OTRS system up and running and I now need to configure it to use the ITSM addons for Asset Management.
I've downloaded and installed these packages using the OTRS Package Manager:

As far as I understand, I now need to configure the /opt/otrs/Kernel/config.pm file, but I'm not sure how. I've tried to edit the file using my otrsuser but am having some difficulty even accessing the file:

Is there a step-by-step guide available on how to do this please?
Sorry, I forgot to list the packages I installed using the OTRS Package Manager. I installed these:
ImportExport.opm
ITSMServiceLevelManagement.opm
ITSMIncidentProblemManagement.opm
ITSMCore.opm
ITSMConfigurationManagement.opm
ITSMChangeManagement.opm
GeneralCatalog.opm