2001 Ford Ranger Fuel filter

My 2001 Ranger bucks and hesitates when I accelerate. The fuel filter has never been changed so I thought this would be the easiest place to start. I went to the parts store and bought a new filter and I also bought a special tool that was needed to remove the fuel lines. It looks like an X with different size holes. I was told to insert the appropriate sized hole of the tool into the fuel line fitting and push it in intil I heard a click. I cannot get the tool to go into the fitting. I've tried lubricating the tool and fitting but am having no luck. Am I doing something wrong, do I need a different kind of tool? I am about ready to give up and take it to a garage. Can you help me?