Hi
This is an old post and the links are not there it seems.
If you search the forum for MPCHG or the web, you will find lots of information.
One search result is:
https://forum.ansys.com/forums/topic/applying-different-materials-on-different-steps/
and for the material ids
https://forum.ansys.com/forums/topic/workbench-apdl-command/
Hope this helps. If not and you need more specific help, create a new post and explain there – this post is closed now as it is very old.
Erik