If you ordered a full hank of casings they normally come wrapped around a couple of rings and then just placed into a package with water and salt. They should be kept refrigerated and every once in a while change the water and add salt. If they develop an odor you need to change the water and resalt.
There may be a secret on removing them from the package. If there is I don't know it yet. But once they are untangled I would store them one or two lengths to a small zip lock so you don't have to untangle again.
First thing you want to do is select a casing and run water through it. This will do two things, remove the extra salt and untwist the casing. The more water the better when rinsing casings. Some people recommend turning the casing inside out while rinsing but I found this to be a bit of a pain and not really necessary.
When you go to place the casings on your stuffer tube look to see if you can load the casing without having to fill the stuffer first. With my little Northern Tool 5lb stuffer it's best to load the stuffer first. Once loaded you want to get as much air as possible out of the sausage. Crank down on the stuffer, pushing the air out and filling the stuffer tube.
If using natural casings keep them wet and feed one end over the stuffer tube. Continue to push the casing onto the tube until you feel you are forcing the casing on or if you are only grinding a small amount of sausage push on only the amount of casing you will need. I am sure someone can tell us how much casing you will need for the amount of meat you use but obviously it depends on the size of the casing and how tight you fill the casings. I used about 3/4 of a length of mid sized pork casings for 12 lbs of sausage.
Once loaded on the stuffer tube, cut of the unneeded casing leaving about 2 inches to work with. Milk out as much air as possible from the free end of the casing and tie a small knot into the casing. You can now begin filling your casing and making your sausage. Fill the casing to the desired length and then twist the newly made sausage away from you several times, fill the next sausage and twist the new sausage toward you. Continue doing this alternate twist until you run out of casing or sausage and have to reload. When reloading pull of about 3 inches of casings, milk out the extra air and tie your final knot as close to the meat as possible. If you have twisted the sausage properly they will remain as individual links as you move the length into a sheet pan and back into the fridge.
Depending on your recipe you may need to mix a bit of water in the sausage prior to loading it into the stuffer to make it easier to push through the tube.
If you have air bubbles in the final sausage it means that the sausage isn't packed tight enough into the stuffer or that you are not filling the casings tightly enough. You can usually push a pin into the air bubble to release the air before smoking
Good Luck,
just ask if you have anymore questions.
Al