How do I do this <a href>?

http://www.twitt开发者_如何转开发er.com/home?status=Check out my page!

However, when it goes to the twitter page, it has %20 symbols replacing the spaces. Why?

Use this instead. http://www.twitter.com/home?status=Check+out+my+page!

Read about url encoding http://www.blooberry.com/indexdot/html/topics/urlencoding.htm

The %20 is the URL encoding for a space. You don't have to worry about that as the web server will understand it properly. Typically spaces are encoded in a URL.