After login into your Muse account, you need to know how to use the basic tools of the Muse. To crop the image, follow these steps:
Step 1 - Go to the "dashboard" and Select background template design.
Step 2 - Then insert the image, by going to the Upload option in the Menu bar, and upload pictures by tapping on the Upload Media option.
Step 3 - Once you insert the image, tap on the edit option
Step 4 - Click on the square icon in front of the Crop.
Step 5 - Crop the image as you want.
Now, you have successfully cropped/resized the image on Muse.