You can create a new WebLingo file or amend an existing one in any editor you want - DreamWeaver, FrontPage, NotePad, Vi etc - but for testing I recommend running them via the Livelink Builder as you can see any error messages that are generated and also any Objects or variables that are available to you and their current values.
To assist developer with getting to grips with working with Livelink, WebLingo and other web technologies, our resident WebLingo Guru - Greg Griffiths - has provided a tutorial on the subject as a walk though of one of the customisations that he has done to his Livelink implementation.
In addition to this, Greg has written a tutorial for using CustomizationsRT, a module to allow you to easily manage, identify and maintain your WebLingo Customisations that you may make.