To upload a file into the Files repository you must have the file saved on your computer first.
Open up the File repository by clicking on the File icon as shown below:
Once inside the Files section you can upload a document straight into this area by clicking on the 'Upload' icon as shown below:
Alternatively you may with to add a file into a folder, in which case just open up the folder to upload your new file into.
Next click on 'Add Files' to select a file to upload:
This will take you into your computers documents - search your documents library to find the file to upload.
Select the document with a double click and then you will see you can then click on the 'Upload' icon to add your file.
The file will show as 100% when it has been uploaded.
Click on Close to return to the main Files section.