In what context - batch or ISPF? What problems are you having? Basically a member is simply a sequential dataset held within another dataset. You specify it like so:
If the PDS exists the DISP is SHR otherwise you need to do all the JCL allocation blurb - disp,dcb attribute, space, volume.
Refer to the JCL Users Guide.
The problem I have is that people can explain things quickly but I can only comprehend slowly.
Regards
Nic