First, you will need to upload the application to Mobile Center. To do so, you will need to log into the Mobile Center server, and click the 'Apps' link located at the top of the console window. In the 'Apps' console window, click on 'Upload Application', which will open Windows file explorer. Locate and select the app file you wish to upload, then click the 'Open' button. Once the upload process has completed, the app will be displayed on the 'Apps' console.
Now to upload the app to the connected device, you will need to do the following. On the 'Devices' console, click the 'Play' button for the device you wish to upload the app onto. In the 'Control Panel' for the selected device, click the 'Install App' button, which will open the 'Applications' console. In the 'Applications' console, select the application to be installed on the selected device, and click 'INSTALL'. The application will be installed on the device selected. I hope this answers your question.