Have A Webcrawler App Which Uses A Web-browser Control To Navigate To A URL?

Basically I have a webcrawler app which uses a web-browser control to navigate to a URL. Once the page is loaded, I use the function below to grab the HTML. Once I obtain the HTML, using HTML Agility Pack I extract the plaintext. Once this is down, with a click of a button I save the url, and plaintext to the database (using sql server).

tb_HTML.Text = WebBrowser1.document.Body.OuterHtml

Now my question is how can I carry the above as a background process, whereby say I have a form and enter all the url I need to extract the plain text from i.e. download the HTML and then using HAP extract the text and then automatically save the result inside the dB.