To create your first Word document on OneDrive start at the My files screen by going to OneDrive
Now decide where you would like to store the new document. It can either be stored in the main My files screen, or preferably in a suitable folder such as Documents, or a sub folder within that. A new folder can be created using the New...Folder menu item. If the new document is to be saved in a specific folder then click and enter that folder now so that the document will be saved there by default. Note that documents can easily be moved into folders once they have been created and saved.