There are two ways to add in-text citations to your paper with EndNote - both methods do the same thing in the end, but the one you use is up to you. This tutorial by EndNote shows you how to use the "Find Citation" command in MS Word 2010.
To use the Find Citation command in older versions of MS Word, follow these steps:
1. In your Word document, select Tools → EndNote X6 → Find Citation(s)
2. In the pop-up box, enter search terms to locate the reference - keywords, author, etc.
3. Click Find
4. Select the correct reference from your search results
5. Click Insert
*NOTE: The EndNote Library you're using must also be open