Before you try upload your work to teams, you should save it to OneDrive.... when you are working on a document, select save as and OneDrive EECD/EDPE will be an option, select and then name the document you wish to save. Hit save. When you open the document from this site it is automatically saved for you as you work so there is no need to save it again. This way you can work on assignments when you feel like it. When you want to upload to teams, go to your specific team, hit assignments, then press add work then upload from OneDrive, where you saved your assignment, then attach, and turn in. 

You are finished!!!