First, what you have illustrated is installing WordPress into different folders on the same domain. Subdomains would be:
Although the folders may be set up the way that you mention them here, you can (depending on your hosting account) set up the subdomains through your hosting panel. For example, with BlueHost you can one-click install WordPress into multiple subdomains, each with a separate database.
On WAMP, you can create new folders in an existing project and install WordPress into those. I’m not convinced these are the best methods.
Good luck!
