First open the broswer and type the following url in the address bar. http://www.mongodb.com/
then you will view the the next page.

click the download mongodb button, and then register a new account, then skip into the following page in above picture, we could fond that there are enterprise releases, managerservice, mongondb drivers and so on, Because of my slow network, now the software is downloading, which may takes about an hour to finish. So in this blog, ijust talk about the download.
the following could be referred to.
http://www.cnblogs.com/mecity/archive/2011/06/11/2078527.html