Step 1: Go to a Document Library that has a Managed Metadata Column and create a folder

Step 2: Click on the Library tab and select the Quick Edit icon

Step 3: Click into the metadata column and type in your Metadata Value and then click on “Stop” to stop editing the list

Step 4: Go forth and create views using the Metadata

There are several tools out there that let you add metadata to your files automatically while uploading them. A cheap yet powerful tool is the office365 bulk uploader which can be found here: http://www.office365experts.be/en/products/office-365-bulk-uploader