Are your friends aware that you're genderqueer but just aren't aware of pronouns? Or they aren't aware at all?
Either way, you could try by just give them a sentence or two about what a pronoun actually is first. I know that before the social justice side of Tumblr, I didn't know what they were.
Tell them about the importance of pronouns if you feel comfortable doing so. Explain She is for (self-identified) girls like Friend Example A and He for (self-identified) boys like Friend Example B and that __(your preferred pronouns)__ is for You. Easier said than done, I know (you MIGHT even need to give quick explanation of non-binary genders).
You should definitely start with the people you feel most comfortable telling and the people who you think would react the best. Build up support just in case there's someone who think may react not so good, and you have a mob on friends who have got your back anyway. It's even worth Googling (or Tumblring) some information about pronouns, binary and non-binary, if you aren't good with words so that you really have to fancy words and whatnot under your belt (not doubting your knowledge of pronouns).
Props for deciding to be open about your pronouns, and I hope all goes according to plan. :)