You really should read the installation directions that come with the plugin
Step 1.1 thru 1.4: directions about creating the directories and copying or moving the plugin files from the restored plugin archive.
Step 1.5
Step 1.5 lib-portalparts.php - Required new library
Copy this file to your geeklog_dir/system folder where the other geeklog library files are
Geeklog components by PortalParts -- www.portalparts.com