i seen this today http://nr11.biz/blogfest/?p=25  and have seen many others like it but how do you take parts from it as they never seem to show you how they do it. im just wondering how they join the two halfs.

Looks to me like the part is made in each half of the mould.  Each part is then bonded together then held in the 2 part mould to align it while it sets.

Not all 2 part moulds are like that.  Often use of a 2 (or more) part mould is done to get round the problem of mechanical lock and release issues on more complicated shape parts. In those cases there is often still access to layup and bag up.