My question solved, check my own answer below..
Hello All.. I'm learning to create module in openERP 7. So I found web_hello module on /usr/share/pyshared/openerp/addons directory. I duplicate it into web_hello2 and change 'name' in __openerp__.py into 'Web Hello 2'.
Following this guide http://acespritechblog.wordpress.com/2012/12/05/how-to-install-new-module-in-openerp-7-0/
I try to click on Installed Modules, after that remove the filter "Installed" and write 'Hello 2' but my module won't show up. Anyone have a solution? Thanks.. :)