The skimmer and possibly the pipe connected to it are leaking. I like to replace the skimmer but I need some directive about how to go about it

Who built the pool? And what kind of deck do you have around the pool? In reality you are better off having a pool professional come out and replace the skimmer. On you pool pump if you have a 100% head of water than chances are that the skimmer and suction side of you plumbing are OK. If you are losing water go to where ever you buy your chemicals and buy a leak locating dye and gently squirt the dye with out moving the water into any cracks or supicious areas. If the dye disappears into the area. You have found the problem and it needs to be fixed. Good luck