Step 1 : Open the item edit screen
Step 2 : Select the ‘Package Item’ check box.

Step 3 : Click the ‘Package’ button at the bottom of the screen.

Step 4 : Click the ‘Select Items’ button then select the items that you want to include this package

Step 5 : Double click the ‘Qty’ column to change the qty.
Step 6 : Click the ‘Close’ button (when you close the screen, the items will be saved automatically).
Step 7 : Click ‘Save’ in the item edit screen.