How do you connect a waterline for a frig. The copper pipe is sticking out of the wall how do I connect the water line

You need to install a stop or valve on that pipe. Buy a stop that will reduce down to the size of the flexible copper tubing you are going to run to the frig. Not a bad idea to add an in-line filter to that tubing at this point. The frig should have an inlet that allows the copper tubing to connect with a not and a flare.

Most lines to an icemaker are 1/4". most connections used to be 1/4" flare. Now, most connections are 1/4" compression. Home depot carries fittings and supply lines for icemaker hookups. You also can get plastic slip fittings to connect pipes together or compression fittings. You also can get a kit with a 10 foot pre-made line that has rubber o rings to make for easier connections. Put a needle valve behind the fridge and bleed out the line before you make the final connection. An icemaker filter does add much to the quality of the taste if you get a carbon filter.