1.Register tag into the page
%@ Register TagPrefix="dnn" TagName="TextEditor" Src="~/controls/TextEditor.ascx"%>
2. Place texteditor
dnn:texteditor id="teBlogEntry" runat="server" width="100%" height="400">/dnn:texteditor>
3. Assign values is same like textbox
teBlogEntry.Text = sdr["Entry"].ToString();
4. Clear text is different than normal textbox
teBlogEntry.RichText.Text = "";