Cross Sell/ UP Sell

Responsibility: Inventory
items–>Master items–>select the inventory org
Press F11 to get into query mode.
Enter a product number and press ctrl+f11
Once the query is executed select the menu Tools–>Item relationships
From item and to item have to be entered along with the kind of relationship as shown below

The following screen shot will show how the products are displayed.

NOTE:Only Related products will work out of the box on 11i instance, iBizSoft does customization for cross sell and up sell to get displayed.