Tutorials webOS Getting Started
This article explains the basics of getting started developing.
Install the SDK
Instructions here for install the SDK.
With Palm official DEB package for Ubuntu, Debian : Installing the Palm® Mojo™ SDK on Ubuntu
With the linux tool alien that convert from DEB package to RPM package for Redhat, Suse, Mandriva : Installing the Palm webOS SDK on Mandriva Linux
Install an Editor
WebOS Internals recommends Komodo Edit and has detailed tutorials for setting it up.
Follow the Hello World Tutorial