Won't shift into reverse or 5th. No power in 1st. Broken plastic thing in engine.

When I pput the car into reverse, it goes forward. When I put it into 1st, it stalls out because I can't get enough power. RPM stays at around 10. So, I quickly shift into 2nd and push the gas pedal all the way down and hold it there for about 15 seconds and the car's RPM will finally go above 10. Then I am able to shift into 3rd as usual and 4th as usual. When I try to shift into 5th gear. It is the same as Reverse. IT isn't there. It seems to be shifting into 3rd instead. I opened up the hood and looked around inside there. I don't know anything about cars. BUT below where the white plastic box with the yellow cap that says brake fluid on it, there are two bars with plastic on them. They each attach to metal bolts on another part. The plastic piece on the end of the metal bar thingies is broken on one of them. It is the piece that has the hole in it so it can be attached to that bolt. Does anyone know what these parts are called? Iattached a picture showing the plastic thing that is broken