[CentOS] centos firewall?

Hi All,

I am new to CentOS and I signed up for a Mosso Cloud Server that runs  
Cent OS 5.2

I can ssh in.

I ran: yum install vnc vnc-server
then: vncserver (and set desktop viewing password)

But I cannot connect.

How do I add 5900 to the centos firewall? How do I edit the conf file?

I only have SSH ability at this point...

-jason