what is a group build

Nah, members here are literally spread out all over the globe, so GB's are geared for online comraderie.

I'd highly recommending joining a couple of ongoing GB's to get the feel for them before starting your own.  It's harder than you think to keep one going.

so you mean they dont get together 'in person' at someones house or someplace they just meet on the forums.

yeah i did have an idea of some sort like to build dioramas based on the landing in normandy on the beaches on D-DAY i thuought that would look pretty-cool

You hit the nail on the head! 

Usually a group of modellers will get together (on the forum) and agree on a common subject which can be very specific or more general (Modern Jet fighters, Soviet T-34 tanks or even a subject that revolves around a specific battle/period like the Korean War).  Several years ago I hosted a Canadian GB where people with an interest in Canadian subjects from Tanks, ships and aircraft could participate.

Rules are usually set such as Aftermarket detail sets are not allowed or something like that but the general idea is to promote interest and discussion about the subject involved.  They are a lot of fun and you get to know more of the other builders on the forum.  Quite often there are badges associated with them for completing a kit, see my scrolling badges for some of the GBs I've been involved in. 

Do you have an idea of something/subject you want to build?

oh and to the FSM forum.