In your HubSpot account, navigate to Marketing > Files and Templates > Files.
If you have a Free, Marketing Hub or Sales Hub Starter account, navigate to Marketing > Email, click the More tools dropdown menu in the left sidebar menu, and select File Manager.
Click Upload files.
Browse your computer's hard drive for files to upload. Select your files and click Open. You can also drag and drop files in the open file manager window to upload them to the folder you're in.