work center tech. data tab settings

Dear Gurus,

I have created work center, now I am using it into Routing of FG material.

when I am selecting this work center then I want that out of many operations only 2/3 operations only performed on this work center and this I want to configure.

For this, I found settings in technical data tab of W.C. at below side there is No. of Processes and also in Menu bar Extras ---> Operations assignments.

Now when I am trying to do settings in W.C., system is not supporting, even not giving any clue.

Plz guide me how can I do this? Is there any prerequisites for it?

Thanks,

Naresh