Step 1 - Download the Mambo template .zip file
Once you have chosen a new Mambo template for your site, you need to download its source file (usually in .zip format) to your local computer.
Step 2 - Go to Menu Site -> Template Manager
Step 2 is to log into your Mambo Administrator panel and choose menu Site -> Template Manager -> Install.
Step 3 - Install new Template
Click on the Browse button and find the Mambo template zip file from your local computer.
Step 4 - Upload File and Install
Click on the Upload File and Install button. If all is fine, you will be forwarded to an Upload Template - Success screen, where you should click the Continue link.
Step 5 - Select the new template as Default
Now you are taken to the Template Manager menu. Please select the new template you have installed via the radio button beside it and click on the Default button. Well done! Now you can see the new template on your site!