HELP threesome any personally advice will be appreciated

Hi all so I have been married for 8 years to my hubby he is the only man I have ever had sex with .. now couple of days ago threesome topic came up and hubby said he is interested and asked me who I'm bringing in... we joked and stopped the conversation there. After that conversation that's all has been on my mind and how interested I am but at the same time I am so scared because I'm not that confident about my body oh and I have always been interested in girls also but never had any relationship so that will make it much more pleasurable right? ... now the question is how do I find that right person? I don't want anyone that we know so we both can be comfortable and not judged. Because I have no experience in any kind of sex and I would want her to take in charge but I have to be center of attention.... do I have to pay someone to join us or is there some kind of website that I can meet them? Sorry for the long post. But I am finally trying to experiment sex.

I am also posting this anonymously because I know couple of people here and I don't want them to know about my sex life