GangadharReddy Create a custom page in Modules->Pages with name 'Chat Support'
and add this code in html view there
<div class="phone phone-use col-12" style="margin:0px"><div class="iframe-wrapper"><iframe title="appIframe" src="paste-your-tawk-to-widget-link-here" frameborder="0" id="appIframe"></iframe></div></div>