In Magento, you can install a new theme by following these steps:
Purchase or download the theme you want to install. Make sure the theme is compatible with your version of Magento.
Log in to the Magento admin panel and go to “System” > “Design”
Click on “Add Design Change” button.
In the “Custom Design” section, select the theme package and theme name from the drop-down menus.
In the “Assign to Store View” section, select the store view you want to apply the theme to.
Click on “Save” button.
After saving the new theme, you need to clear the cache. Go to “System” > “Cache Management” and select “Flush Magento Cache” and “Flush Cache Storage”
Go to the front-end of your store and check if the new theme is applied correctly.
Note: You can also install a new theme by uploading the theme files to your server. You will need to upload the theme files to the “app/design/frontend” directory and then follow steps 3 to 8 to assign the theme to your store.
It’s always good to take a backup of your database before making any changes and test the new theme on a test environment before applying it to the live website.
