Help in understanding this code

Hello and good morning, I have a html editor that when i store the data, it will have the html <br> instead of <p>. In this html editor website im using I found I code that describe what to do to change from <br> to <p>. But I am confuse on the word bolded in blue, 'Enter'. The part with comment, '// If 'Enter' was pressed', does it points to a button assigned/connected to the html editor?? If it is, my Button ID is Button1, where exactly do I have to place the ID, to allow the javascript to run when the button is click?
This is the link: http://www.obout.com/Obout.Ajax.UI/HTMLEditor/KnowledgeBase.aspx?id=959
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