Step 1. Check Permissions
Make sure the ''app'', ''js'', ''lib'' and ''skin'' directories of your Magento®, as well as their individual sub-directories, have full "write" permissions. This is necessary to ensure that you will be able to upload the extension files to these directories.
Read more about permissions at http://devdocs.magento.com/guides/m1x/install/installer-privileges_after.html
If you experience any issues with the files upload, set permissions on the above mentioned directories to “700” according to the documentation of Magento® and try uploading files again. Make sure to write down or memorize what permissions were set previously, so that you could change them back after the installation has been completed.
Step 2. Disable Compilation
Log in to Magento® Admin Panel, go to System → Tools → Compilation and disable compilation.
Screenshot: Disable Compilation
After Step 5 you can run the compilation process again.
Step 3. Upload Files
Upload all folders from the extension package to the installation directory of your Magento® software using an FTP client.
Screenshot: Uploading files
Step 4. Clear cache
Go to System → Cache Management and clear the store cache.
Step 5. Re-login
Log out and log back in to Magento® Admin Panel.
If you see a 404 error page, please re-login.
Step 6. Use Extension
Go to System → Configuration.
In the left column you will see a new tab – GOMAGE.
Screenshot: GoMage Tab
At this point you must activate the extension!