Uploading files in Moodle is, unfortunately, not as easy as weí would like (However, feature requests for drag and drop in future have been made). You can upload several files to Moodle at once if you use zip. Zip the files on your PC and upload the zip file to your Moodle course. In your course sites files in Moodle, you will see an "unzip" option next to the file. This can be used to transfer (for example) whole websites into Moodle.