If you install the MS Word plugin, you will be able to take advantage of the cite-while-you-write (CWYW) features using your EndNote Online library. Otherwise, you can export a list of reference in a selected bibliographic style and paste them into your document.
Note that from the EndNote tab in Word you will be able to select whether you wish to use your Online Library or a library from the desktop version of EndNote if you are using that as well. From the tab go to preferences then select the application tab from the pop-up window in order to choose which version of EndNote you wish to connect to that particular Word document.
Login to EndNote and go to Downloads and the Cite While You Write section.
Download the appropriate installer and follow the installation instructions to add this plugin to your Microsoft Word installation.
Once it's installed, you'll need to configure the plugin. Open Word and look for the EndNote menu. On Windows it's a top level menu item in your ribbon. On Mac it's under Tools.
Then select the Application tab, choose EndNote online, and enter your Endnote username and password.
Once you've added references to your library, and configured the plugin you can start using EndNote to insert in-text citations and create reference lists.
To insert an in-text citation, find the appropriate point in your document, and click the Insert Citation button on the EndNote toolbar.
Type some words from the citation you're looking for (the author is often a good choice), select the citation to be added from the list and click Insert.
The in-text citation will be added where your cursor is in the document, and a references list will be started at the bottom.
You can change the citation style by using the Style drop-down.
If you use a word processor that isn't Microsoft Word, you can export a list of references with your preferred citation style applied, but you won't get the tight integration between EndNote and the word processor that you would have with Word.
If you want to use Google Docs to write, you might want to consider Zotero instead.