Firstly, log into office 365 at office.com, from your home screen open One Drive by clicking on the icon.
Select upload at the top of the screen and select either Files or Folder.
You can then select either the File or the Folder you wish to upload.
This will then upload the file to your one drive.
To access these files on another PC log into Office 365 on that PC and go into your One Drive, if you click on the file it will open in Office 365 if possible. You can download it by right clicking on the file and selecting Download, the file will then open on an appropriate program on that PC and you can then save this file to the PC.