There is a fantastic extension called Chrono Forms. http://extensions.joomla.org/extensions/contacts-and-feedback/forms/1508
You can download it for free for any version of Joomla: http://www.chronoengine.com/downloads/9-chronoforms.html
The extension comes with video tutorials which will guide you step by step, easy to follow, and good support. Just browse the www.chronoengine.com website, or ask questions in their forum if you run into any complications while creating your form.
I've created many forms using this extension, contact forms, newsletter subscription forms and so on. The extension offers high customization, and it also has Captcha, recaptha or honey trap options to avoid spam upon submission.