There are other skills plumbers need aside from being able to work with water. One of the most common things that a water softener on is fixing water lines.
With a putty knife, carefully scrape the remaining parts of the wax ring from the area. Clean the spot so that the new wax ring will be level. Place a new wax ring on the opening and replace the toilet. Bolt it back onto the floor, reconnect the water line repair supply tube and watch for leaks as the water is turned back on.
One other common design that is considered "washerless" was made famous by Delta and copied by several other makers. It uses little "cup" seals that fit over springs recessed in the back of the valve body. The springs press these "seals" against the cartridge and regulate the flow through little tapered openings in the cartridge. If you have one of these and it's dripping, changing these springs and seals will usually correct it. Here's a tip. Once you have the cartridge out of the way, insert a phillips screwdriver into the seal and pop both the seal and spring out. Stick the new ones on the end of the screwdriver to help guide them into place. This is especially helpful if you don't have long slender fingers.
Clean the hole in the gutter railing first. It must be free of any debris, so you may want to clean the entire drain channel using a proper cleaner. In this way, you will have a clean surface area which will allow you to repair the hole more easily.
As with anything, when you are not sure how to fix a plumbing issue and when you don't have the proper equipment, you should contact a professional. They can usually find out what the problem is and resolve it for you in a short period of time. They will also be able to tell you if you have any other problems and water line repair they can suggest resolutions.
The work area should always be clean and free of trash and clutter. The cleaner and less clutter there is in a Plumbers' work area, the better able a plumber will be to make sure that his job goes as smoothly as possible.
Then, you can take your new shower parts home and reinstall them in the inner assembly. It is very important that everything be aligned properly and tightened to prevent leaks. Beware of over tightening, however, since this can also cause problems. Once you are sure everything is installed properly, replace the cover plate and turn the water back on to test your repair work. With a little bit of work, your do-it-yourself shower repair project can be a success. It does not take an expert, just a little effort and know how.