Sending emails from php script

Hi all!

I bought VPS in OVH and it looks very nice, I also bought a domain and emails pro in OVH. I added VPS's IP address to domain DNS zone, installed apache2 on VPS so I am able to have webpage on my VPS and under my domain. I created email account using my Panel and I am able to send message from it to my other gmail account. I would like to have an opportunity to send mails from VPS using PHP script and mail() function. How should I do that? Should I install some kind of mail server like postfix or sendmail? Should I configure it using my previously created mail account? I would like to host a website with the possibility to register users and send them activating link via email. So far without success...

Thanks in advance.

BR
Mateusz