Sign up once

[Unbreakable]

I wanted to set up an arcade script plus a forum on my website. However, how would I go about making it so a user would only have to sign up once and it would count for both the arcade script and forum. Could someone explain to me how this could be achieved/how long it should take. (I don't have any php knowledge, but I figure this could be a good learning experience.) Thanks.

 

The arcade script: https://secure.agaresmedia.com/v6/free-stuff/download-arcadem-le-arcade-script-for-free/

For the forums I was thinking about using SMF.