I need help with a contact form (simple)

I have created a contact form using PHP, Java and HTML - I am not very experienced tho, so when I finished it I have posted a question on codereview.stackexchange.com seeking some feedback.

Please view this link for the code: http://codereview.stackexchange.com/questions/39103/how-to-improve-this-current-contact-form/39118?noredirect=1#39118

I just simply want someone to help me enhance the form and secure it. Open to pay more if needed.