If your Webpage has a submit link button on it you can click here copy and paste the URL from your hub pages profile here and click save. If you have access to your admin area of your website you can edit the text of a page to include your Hubpages URL.
If you mean how to do it in hubpages type the name of your website in the text box click and highlight it then there will be a chain like image appear on the top of the text box click here and a small box will appear. Type the URL of your website here and then press insert link and then save the text box. Hope this helps.