Magnolia 4.5 reached end of life on June 30, 2016. This branch is no longer supported, see End-of-life policy.
To update your Magnolia to a more recent version:
WEB-INF/libdirectory of your Magnolia instance(s) by the new ones found in the bundle you just unpacked. Make sure you remove any module you had previously removed from your instance(s) and re-add any extra module you might have added as well.
indexfolder under each workspace directory:
repositories/magnolia/workspaces/website/index, and so on. Indexes will get recreated on startup, which might take a while, depending on the size of your repository.
magnolia.propertiesfiles, please compare the changes you made with the new corresponding file. New properties might have been added, some might have been removed. This will usually be specified in the release notes of the version you're installing.
Please see the release notes pages for update instructions specific to the version you are updating to. If you're skipping versions (if you're updating from a fictional 1.2.3 to 1.2.6, for example), please read all release notes concerning the versions you're skipping too.