F1 Help documentation

Hi,

I have a checkbox using parameters statement on selection screen.I need to create Help documentation on F1.

Can anyone tell me how to do that.I read one of the thread and tried the goto->doc->data elem doc. on screen painter.but since the screen is not custom screen I get a warning as

"Selection Screen:Report generation makes changes ineffective". So I am not sure if i can do the documentation on the screen painter.Let me know the other way of doing.

Thanks

Suganya