basically just use a showstats(); function in a system NPC (npc that is added to everyone on login)
http://wiki.graal.net/index.php/Crea.../Script/Client
scroll down to showstats and it will explain how to use the function.
then, a GUI is basically just an image. you use showimg() to display the image and showtext() to display info on the gui.
this is a very brief explanation but I hope I helped
