I am new to apple and I want to use iMessage. When I am connected to the internet, I thought SMS would automatically send as iMessage. The one I'm texting also uses iPhone 5 and we're both connected to internet. I still have to know what their e-mail to text them in iMessage.
You can go to Settings > Messages and turn the Send as SMS option off. (The actual names of the options may be different as I am just translating from my local language settings.)