- Rename the current program folder MAMP to MAMP_OLD
- Load the installation image of MAMP from http://mamp.info and open it
- Drag the MAMP folder from the installation image to your "Applications" folder
- Copy the directories "htdocs" and "db" from your MAMP_OLD folder into the MAMP folder. It contains your personal HTML files and database contents. Overwrite the folders in the new MAMP folder
- Check whether all data has been transferred correctly
- The MAMP_OLD folder can now be deleted. You may however keep it, so you can fall back to your original setup