onClick Allow Input Selection

Hey! I'm making a form and I would like to use an onClick script. I have never looked into onClick features before, and I suddenly need help.

I want my form so when you click 'Yes' on the drop down menu, the function enables the input below it which is another drop down menu with the choices yes/no. And if you select 'No' on the drop down menu, the input below it is in a grey shade and is disabled.

Please help
Oli.

It might help if we knew the code you were coding in.

HTML.

html message is too short

Though it was rather obvious that I'm coding in HTML.

Well, as soon as I seen onClick ; I thought it may have been Lingo.

the onclick is a html functionamabobby but it uses javascript inside it.. there is a tut on this on www.htmlgoodies.com I think