Start -> All Programs -> Accessories -> Command Prompt, or start and type "command prompt" in the search field.
This really isn't a question related to Java so you should sometimes ShowSomeEffort and try to google when you come to issues like this. You would probably get answer(s) like these faster than waiting for a reply here.
In addition, I followed some of the topics you created and checked some of them you started earlier. What I got is that you don't really obey to the forum rules, so I would suggest you read How To Ask Questions On Java Ranch entirely if you expect to get any further help.
The quieter you are, the more you are able to hear.
subject: How To access the DOS Command Prompt in Windows 7