There are two ways to share a file via OneDrive:
1) Via OneDrive on the web: 
2) Via local Windows File Explorer

Method #1
Step 1: upload the folder or file to OneDrive. 





Step 2: share the document by clicking Share


Step 3: fill in the details as to the message (if you want to send one), the email address of the person who will get it, and click the Eye icon to ensure the setting "Can edit" is enabled. Then, click Send.




Method #2:
An alternative way to send is by going to Windows File Explorer. Clicking into the OneDrive section where you have the file stored or create/move it there (it will have a blue cloud filled in) and right click the file/folder and select Share. A window will pop up allowing you to fill in the information similar to above: