It’s a funny world when we have to learn how to use fresh ingredients rather than canned/processed/manufactured. But you can take heart in the knowledge that your home-grown stuffed chiles will taste much better than canned ever could.
To use them in your recipe, you want to remove the tough skin, the seeds and the ribs. You really should wear rubber gloves to work with chiles; their oils are extremely potent - and make sure not to get them, your hands, or the gloves near your eyes, nose, or mouth.
To remove the skin, cut a small slit close to the stem end of each pepper so that steam can escape. Then place them on a baking sheet under the broiler, on a hot grill, or directly on the burner grate of your gas stovetop. You want them to blister all over, so turn them frequently. Remove the peppers from the heat and immediately place them in a paper bag and close the end, or wrap them in damp paper towels and place them in a plastic bag. Let them steam in their own heat for 10 to 15 minutes. After you take it them out of the bag, you will be able to pull the skins right off.
With a paring knife, cut a slit lengthwise in the chile about 1/2-inch from the stem. Use a small spoon to scrape out the seeds and the veins. Then use the same opening to stuff the peppers, as specified in your recipe.
By the way, for a fun fact to know and tell: your long, green Anaheim peppers are really New Mexican peppers, but were dubbed Anaheims because of a popular pepper processing plant that popped up in the city in 1900. People may argue with you about it, but you can take comfort in the fact that you are right and they are wrong.