The process for adding a file to Moodle is called "uploading" and is always the same regardless of what kind of file you are working with. This video will walk you through the process. Even though it is specifically about uploading a course syllabus, it holds true for all file uploads. Please refer to this video anytime you need help uploading a file.
You can upload any file type to Moodle to give your students access to handouts. In your content block click the "Add a Resource" drop-down menu and select "Link to a File or Website". Name the document and write a description. Where it says "Link to a file or website" click the "Choose or upload file" button. A new window will open with the Moodle file manager. Click the "Upload a file" button and then "Browse" to navigate through the hard drive to where you saved your file. Select the file, click the "Open" button and then "Upload this file". Finally click "Choose" next to the name of the file.
There are a few options that are useful for students. Under "Window" there is a checkbox for "Force Download". This will allow the file to be automatically downloaded onto the student's computer and displayed in a browser window when they click the link. Some web browsers do this automatically, but clicking this box will ensure that all students have the same experience when they use your page.
At the bottom of the window click "Save and return to course". You will see your file now appears in the content block. If this is your first file upload you will also notice that on the left hand "Activities" block there is now a link for "Resources". Here you will see all the resources for the course, listed under the Name you gave the file, with the Summary that you typed in when you uploaded it.
You can upload files individually, or you can upload multiple files or folders of files. To do this go to the Administration block on the left hand side and click the "Files" link, which will open up the File Manager. Here you will see all the files you have uploaded. To organize your files you can create folders. Click on the "Make a folder" button to create a series of folders to organize your files.
To upload files to a particular folder click on the link for that folder and click the "Upload a file" button and follow the same steps you used above. To go back to a previous folder click on the "Parent Folder" link. These files can be accessed by clicking on the "Resources" link on the left hand side of the main page, but you can also post them directly to your weekly content blocks.
To post an existing resource in a content block click "Add a resource" and select "Link to a file or website". Name and describe your resource and click "Choose or upload a file". when the file browser comes up you will see all the files you have uploaded so far. Navigate to the file you want to post, but do not click on the file name - that will cause the file to download to your computer. Instead click the "Choose" link to the right of the file name. Back at the File Browser don't forget to select Force Download before clicking the "Save and return to course" button. On the main Moodle page the file now appears in the weekly content block as a download link. It will also be available in the "Resources" page on the Activities block to the left.