Material doesnot exist in warehouse

I created a Purchase order and now i am trying to do a GR for the material. It is giving me the following error. "Material 3300-270 does not exist in warehouse 088. " How can i fix this error?

This is the first time i am creating a goods receipt for this PO. How will it exists in warehouse?

I wonder do we have to assign any warehouse or storage location for each material when we create? Is it compulsory?

Guru's please help me with this. Thanks. I appreciate it.

Madhu