Setup server with Dyndns

Hello everyone, ive recently buy a Mac Mini wth snow leopard server, I dont know anthing about servers, but apple said it was a piece of cake, well for me is not, and as ive read many forums, people recommend to install the server yourself, so I did it, but I can get to run my services correctly, I dont have a static address, so i am using dyndns services, my question is how to configure correctly using dyndns to have a running server ( i have two small offices which i want to connecto to the server) I have no solid knowledge on servers

Thanks in advance!