I need to add a text box and based on what the person types it needs to reditect

What I’m trying to do it create a type of “Promo Code” text box. So I need to enter a text box and be able to control what words it accepts and when someone types in that word it will redirect them to the correct page.

For example a text box that if the person enter “promo15” they will be redirected to https://www.website.com/promo15

or if they type in “save100” they will be redirected to https://www.website.com/save100

or if they type in anything else they will go to https://www.website.com/wrong-code or something like that.