pressing F1 in WED will solve all problems
you have to create a PANEL. assign a background-image (your splashscreen-image) and set it visible. then, if you want to hide it, set it not visible (you can do it using the "flags"-parameter)
for further instructions refer the manual. there´re also example code about creating panels
this is a question, which is asked very often. if you follow michaels adivce, you will maybe find a complete code-snippet