Figuring out how to open the place on my cell phone where the adapter plugs into

Today I tried to charge my cell phone in my car, and for some reason it was confusing for me to do so. I had to figure out how to open the little place where the phone adapter plugs into. I knew where the adapter went into the cell phone when I needed to charge it, but I had trouble figuring out how to open this little piece that you have to move in order to plug it in to charge it. Thankfully, eventually I was able to figure it out so that I could charge my cell phone.