Hi
I thing you have to type the command "APYSIDKRN" could you refer the SAP Note for Kernel steps -
1713986 - Installation of kernel 721 (EXT)
1432807 - IBM i: Applying a saved kernel using APYSIDKRN
1632755 - IBM i: Description of command APYSIDKRN
1097751 - iSeries: Information and recommendations for kernel libraries
Regards
Sriram