how to enter special character on a PDF form

Hi erveryone, I am newbie and not really tech savvy. I am completing a PDF form but is unable to enter special character in some fields as well as numbers in some feilds that I need to put a number. For example a middle name that is hyphenated I am not able to put in the hyphen or a field where i need to put in both letters and number I am getting a message saying " Java script window, enter only letters"  Can someone please help me out.