How Can I Improve My PC Muscle?

Hello Betty, I am so very happy to have found your site a few years ago. I have learned a lot!
What is the best way to go about 'fixing' my PC muscle? I have been with the same partner for nearly 15 years and we have had three kids. I am 33, my youngest is six. I have never done anything to help myself along the way, now I'm in panic mode.