Follow these simple steps:
1) Go to the "Plugins" menu and click on "Add new" on the top of the page
2) Here you can install all the WordPress Third Party Plugins. From here you can also install the MusexPress Official Plugins. To install an Official Plugin click on "Upload Plugin" on the top of the page
3) Choose the .zip file in the Plugin folder and click on the "Install Now" button
4) Click on "Activate Plugin"
5) All is done on the back-end side. Remember to configure all the Muse Widgets of each Official Plugin (to know how to do this, look at the specific Plugin documentation page).
Watch the complete video tutorial