If you are asking this question in the context of writing your own DNN modules, this tutorial from Michael Washington gives information on various ways to navigate from module control to module control, etc. The most commonly used method is to redirect to a url built using the EditUrl or NavigateUrl methods or as an item added to the module's action menu:

http://www.adefwebserver.com/DotNetNukeHELP/Misc/ModuleNavigationOptions.htm

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Bill, WESNet Designs
Team Lead - DotNetNuke Gallery Module Project (Not Actively Being Developed)
Extensions Forge Projects . . .
Current: UserExport, ContentDeJour, ePrayer, DNN NewsTicker, By Invitation
Coming Soon: FRBO-For Rent By Owner