help on function script

help on function script

Hi, 

Can you please help me to make a function to perform below task?

Module Name: CustomModule5
Percent Field called Discount
Text Field called Wording

If the input of the Discount field is either Null or its value is 0, then value of Wording is set to empty,

If the input of the Discount field contain value, then value of the  Wording field change to "Discount :" + value of  Discount  field.

e.g.

If discount is 5%, then the Wording is set as "Discount : 5%"
If discount is 0, then the Wording is set as "".

Thanks!
br, Andy