Select a file or folder.
Press the sharing icon to show the sharing options.
The following manual is showing the steps for sharing an folder. If you want to share a file, please follow the same steps of the file level.
Enter the desired mail address. Choose the option which is shown with "(email)".
An email with the link is sent to the recipient.
The email address is shown in "sharing" and the rights can be set accordantly. The sharing can made undone by selecting "unshare".
To read more about the password protected sharing or setting an expiration date, see the other manuals.