How do you create a signature on the Samsung Strive phone?

So I have the Samsung Strive (From AT%26amp;T) And I can not figure out how to create a signature on there! I've looked everywhere and cant seem to find it! Does anyone else know how?|||Hey. Go to messaging then go to Message settings. If you dont see it there your phone prolly dont have signature. Thats how most Samsung cell phones are.