Copy the contents of your old config.php into your new config.php.
Upload (overwrite) all new version files over the old version files When you are done uploading, delete /install/install.php.
In your browser, run h t t p://yoursite/install/upgrade.php.
Note: if you have done any mods requiring file edits, they will disappear when the new version is installed, so be sure you have instructions handy on re-doing those mods.