Web version of the endnote can not add a new template, only with the template Library of those, so instead try the offline version of the client.
1. After the download installs (will not give, there are many online), in Word can see the top bar has plug-ins, if you also installed the online version, you need to switch:
2. Import the required format:
How to use endnote to import the format of one of the journal you want to use.
(1) Open endnote, click Edit-output style-open style manager-get more on the web.
(2) Go to the Web page and look for the format of the journal Endnote you are looking for, download, save in the local folder.
(3) Open the format you already download, click File-save.
Double-click to open it.
(4) Enter Endnote-output Style-open style manager again to see the journal format you have downloaded. Put the hook on the small box in front of the format.
(5) Finally, in the Endnote interface drop-down menu, select the journal format you just clicked. Finally, in Word format, remember to write this format.
Reference: http://muchong.com/html/201006/2175899.html
Endnote X7 How to use