Here is a quick and short video by Synergy Learning showing the simplest way to add a file to your Moodle course page by drag and drop the file onto the course page.
Here is the direct link to the video and this is the official Moodle docs link about working with files.
Jaswinder Singh, passionate about using Moodle in improving the Indian Education System and reaching the students in far flung areas where still education seems to be a impossible prospect of life. He is the author of the popular Moodle Book "How to use Moodle 2.7". In October 2016, Jaswinder was elected as the Moodle User's Association Committee member - the first to make it from India.