<script src="http://js.nicedit.com/nicEdit-latest.js" type="text/javascript"></script>
In the <head> tag of design page create JavaScript function as:
<script type="text/javascript">
bkLib.onDomLoaded(function () {
new nicEditor({ fullPanel: true }).panelInstance('txtName');
});
</script>
OR
if you use master page then you have to use this script<script type="text/javascript">
bkLib.onDomLoaded(function () {
new nicEditor({ fullPanel: true }).panelInstance('ctl00_ContentPlaceHolder1_txtName');
});
</script>
In the <body> Tag place a Textarea
<textarea id="txtName" type="text" class="input_txt" runat="server" style="width: 420px;
height: 60px;"></textarea>
reference link
Click here read article
