Basically, in order to tie your domain to your web ip, you do need dns. In other words, you have to follow all those steps except steps 8 to 10 because you've already had folders and websites; however, before follow that step 11, you need to do an extra step that Cyber missing which is to enable httpd-vhosts.conf, so open httpd.conf in wamp/apache2/conf, then find and take out the # sign in front of the line that mention the file name httpd-vhosts.conf.
For dns, you can sign up for free account at dyndns.org, everydns.net as cyber recommend, or zoneedit.com, my favorite dns, and of course, most of them have similar functions, maybes just different design.
Have fun,
[www.jlbn.net] (testing WAMPS)[test.jlbn.net] (testing codes)