You can use regular expression to extract HTML tags from a string of HTML. There are millions of example on the web. Here is the one I found via google:

http://www.4guysfromrolla.com/webtech/042501-1.shtml

>Hello
> Current i writing a c# program and I want to get some text from html files. But all these data are insdie some HTML tags. Is there any way in c# can let me detect some tags and get the data within that tags.
>
> Best wish and regards!