You enter the path of a directory and a file pattern (*.rpm) and linuxconf will find the list of packages in this directory that are different from the currently installed packages on your computer.
The directory field has a help list. This list is set with the various directories entered in the preference dialog.
Three checkboxes let you control the selection. Those checkboxes may be used in combination.
Managerpm only shows package versions newer than the one installed on your workstation. Sometimes, update directories contain older versions when the vendor finds out that downgrading is better (because the current version is known to be too buggy or have security flaws).
A checkbox expands the view, showing older versions of the packages.
By default, managerpm only presents the package candidates for updating: they are already installed on your system and a newer version is available in the directory. A checkbox lets you expand the view by showing packages which are not currently installed.
Normally, only the newest version of a package is presented. Managerpm silently removes the older version from the list. This checkbox will disable this behavior. Normally, you'd use this if you're unsure whether you want to upgrade to the newest (and potentially buggy) version.