First thing, it's not official exchange list from bitcoin developers.
It just 3rd party website made by someone to help us searching bitcoin exchange in some countries.
Second thing, that site didn't have contact page so you can't contact them to put your own website (or an exchange maybe? ) on their list.
Best way is develop and promote your website and make it popular and trustworthy on your country. I'm sure howtobuybitcoin.info admin will notice your website and put it on your list
Good luck with your project
