Contact form settings are on the Appearance->Theme Settings page;
If you filled all required fields correctly and if it still doesn’t work, please contact your hosting provider. There should be a problem on your server.
If you can’t solve the server problem, you can try the followings;
1) You can search for a plugin. For example; CONTACT FORM 7
2) You can use an online form builder like JOTFORM
If you are an unexperienced WordPress user, I suggest you to buy a customization service from Envato Studio to add a custom contact form to the theme; CUSTOMIZATION