To create a forum, make sure edit mode is turned on, and click the “+Add an activity or resource” button located at the bottom of each week/topic then select forum from the list. You can select a forum type by expanding the “Forum Type” drop down menu in the General section.
The default is “Standard Forum for General Use,” and that works for most scenarios. 
The Q and A forum type can also be useful. There are a few key differences between this forum and the standard forum. In a Q and A forum, the instructor must post a question first, and then in order to see their fellow classmates’ responses, students must first post their own response. To post the question(s) that you want the students to answer you first create the forum, then go into the forum and click the “Add discussion topic” button. It you don’t ask the question by starting a discussion topic the students will not be able to reply with their answer. This is a good way to ensure that students are posting original content, but note with the Q and A forum there is a 30 minute editing window where students can modify their post before it is submitted and locked.
By default, students are allowed to upload files to their forum entries, and the default file size settings will work for most moderate-sized uploads (like documents and images). If you want to prohibit students from uploading files, expand the “Attachments and Word Count” section, and make sure “Uploads are not allowed” is NOT selected. If you need to expand the file size limit on uploads, you can do that in this section as well, but you should consider contacting your Instructional Technologist to see if there is a more appropriate tool to use for your envisioned activity.
There are a variety of other settings that allow you to specify response windows and cut-off times. You can even post audio files to discussions. Full documentation on the Moodle options for this tool can be found at this link: https://docs.moodle.org/401/en/Forum_settings.