Galaxy S3 authentication error

[Koyoo]

Im dumb with technology so please say it in a way I can understand. So my phone will not connect to any wifi, it just keeps saying authentication error. Why and how do I fix it?

 

[B. Diddy]

Welcome to Android Central! That might mean that the wi-fi password you're entering is incorrect. Have you double-checked to make sure it's correct? Are you missing a capitalized letter somewhere?