Thank you for your interest. It used to be a very time consuming process of turning the lens focus ring a small amount and then take a shot, making sure the camera and subject did not move during the time it took to take all the shots. That was before I got my Olympus EM5II which has a focus bracketing feature which is brilliant and saves so much time - recent Panasonic cameras also have this feature. Here are some tutorials I made a little while ago if you want some more detail.
https://steemit.com/macro/@brianhphotos/focus-stacked-macro-25-basic-steps-tutorial
https://steemit.com/macro/@brianhphotos/focus-stacking-tutorial-part-1-why-focus-stack
https://steemit.com/macro/@brianhphotos/focus-stacking-tutorial-part-2-equipment
https://steemit.com/macro/@brianhphotos/focus-stacking-tutorial-part-3-how-i-shoot-my-indoor-image-stacks
https://steemit.com/macro/@brianhphotos/focus-stacked-macro-58