On your fileserver locate the folder to be shared, right-click and choose Properties.
Click on the "Web Sharing" tab (* if the Web Sharing tab is not available see the note below) and select the "Share this folder" radio button.
Check that the WebDAV service is enabled: Open the IIS Manager, select the Web Service Extensions folder. The WebDAV item listed on the right should be set to Allowed.
You can check that the folder has been correctly setup as a WebDAV share by opening your Internet Explorer and clicking File and then Open, tick the "Open as a webfolder" box and enter the url in the format http://server.domain.com/share. The share should open in a format that allows you to open and modify the files.
* If the Web Sharing tab is not available you will need to install the "WebDAV" component of IIS:
Go to the Control Panel then Add/Remove Programs and Add/Remove Windows Components
Under Application Server go to IIS and then World Wide Web Service and tick the WebDAV Publishing box (fig.2).