Instructors often allow students to submit assignments online through assignment dropboxes which can be accessed through Moodle.
To learn how to submit an assignment on Moodle, follow the instructions below:
Click on the assignment dropbox for the particular assignment that you wish to submit.
For uploading files from your computer, Select "Upload a file", next "Choose file". Locate the file your wish to upload. Click "Open", then "Upload this file". It might take a moment to upload.
Once you have competed the task and uploaded the file you desire, you should see that the assignment is marked as "Done" automatically.