It's not only setting the permissions to 755 (which you've already done), but did you enter all the info to the config file itself as the instructions said (read #12 of the instructions)?
Make sure you use the variable names as you have it in your form (ex: Real_Name, E-Mail). Note, you are using "E-Mail" with a hyphen and the instructions doesn't, so you have to make sure that you make the appropriate changes so the script reads the variables correctly.
Sorry, but from here on, someone who actually uses the TFMail script has to help you. I do not use that script for my forms, so other than what I'm reading in the instructions, or knowing what needed changing for your html page, I can't help you too much further.