GO this address and follow the steps
http://www.endnote.com/support/faqs/CWYW/faq1.asp
However I will post the require steps here
If the CWYW tools do not install for any reason during program setup you can manually install the tools by doing the following:
1. Within Microsoft Word go to the Tools menu and select Options.
2. Click the File Locations tab, highlight the Startup folder, and then click the Modify button.
3. Note the path to the Microsoft Word Startup folder. If no path is listed at the bottom of the window click on the “Look In” dropdown at the top of the window and note the path.
4. Close Word
5. Launch Windows Explorer and locate your EndNote folder. The default installation path is “C:\Program Files\EndNote”.
6. Copy these two files ( this is for windows XP/2003)
EN7CWYW.dot
EN7Cwyw.WordXP.wll
This is for windows 97/2000
EN7CWYW.dot
EN7Cwyw.wll
If you do not see the .wll and .dot file extensions, go to the Tools menu and select Folder Options / View tab. Uncheck the box that reads “Hide file extensions for known file types” and click OK.
7. Locate the Word Startup folder and paste these two files into this folder. If you cannot find the specified folder, your Windows preferences may be set to hide the folder. In Windows Explorer go to Tools / Folder Options / View tab and make sure that "Show hidden files and folders" is selected.
8. Launch Microsoft Word.
Before you use the tools for the first time, close Word, then open EndNote and an EndNote library, then re-open Word and click on one of the EndNote tools. The programs must only be opened in this order the first time you use the tools so that Windows will be configured correctly.