How to setup a coupon

I have the following scenario:

we want to give a 10% off to everybody of our facebook friends.
So: in regards to our nopcommerce site  the (facebook) user is not known.
How do i generate a coupon code (which will be given to our facebook friends), so she (hopefully) will buy something in our webshop?

I hope i 've explained as close as possible!
Thanks in advance

ssopiadis wrote:
In Admin>promotions>discounts>add new button and check Requires coupon code:

I see!
But this way EVERYBODY who has the SAME coupon code will get the discount. So: if somebody gives this coupon code to her neighbor, then the neighbor also will get the discount. This is something i don't want.
Isn't there a way to create, let's say, 1000 unique coupon codes which will be sent than to our customers.
Upon usage of this coupon, the coupon gets invalid.
Is this possible?

You can select one time per cusyomer condition

And where is it possible to create coupon codes?

ssopiadis wrote:
https://www.nopcommerce.com/boards/t/18705/suggestion-a-simple-way-to-generate-massive-and-personalized-discount-coupons.aspx

I want to setup a coupon about Funmi hair, Brazilian Body Wave, Lace Front Wigs, and a coupon about Toupees, Men’s Hairpiece, Non-surgical Hair Replacement, but I can not find the right place to setup  coupons. Anyone can tell me where is the entrance of coupon sending?

In Admin>promotions>discounts>add new button and check Requires coupon code