You can add citations by hand by clicking on the + icon (plus sign) at the top of the page. 

In the menu that appears, select how you would like to add items. You can drag documents right onto the RefWorks page to import them automatically, or you can import from an existing file.

If you would like to enter the citation information by hand, click on Create new reference. Select the type of reference you would like to add. The required information will change based on what type of citation you're adding. Click Save when you're done.

For items found in the Libraries Search or in reference databases, it may be easier to import references from the catalog and databases directly.