Hi Blangero,
not exactly sure what you mean by: "I want to get WebGUI URL from ABAP, like to read from some table"
What are you hoping to do? Run a report that will execute the WEBGUi service and pass parameters to it?
The ITS WIKI is a good resource
http://wiki.scn.sap.com/wiki/display/HOME/Internet+Transaction+Server
for example check the following WIKI:
How to prefill fields and skip first screen with webgui? - Wiki - SCN Wiki
Regards,
Oisin