When something's wrong inside the toilet tank, it often doesn't take a professional to get in there and fix the problem. Lots of times, a homeowner with the right savvy and a few basic tools can get to the root of the problem. This will save the household a lot of dough and prevent the need for a trained plumber to schlep all the way across town. When conquering an unknown dilemma in your tank, you'll first need to get good access by clearing the entire area and taking off the heavy porcelain top, and setting it aside. It may be good to lay down newspaper or some other substance to set the tank lid on, and if space is an issue, be sure to move all of the objects around the toilet to prevent annoying access problems. You may also want to get into the habit of keeping a flashlight around in case the interior of a tank or another area does not have sufficient light.
As far as tools, a pliers and screwdriver as well as an adjustable wrench are good ideas. The most you will likely have to do is to loosen a nut fixing one or the other of several parts to the tank system.
You'll want to drain the tank to be able to work inside. To do that, first find the shut off valve for the toilet. It can be found near the inflowing water pipe by naked eye. When you've turned the valve off, you can flush the tank, and it will not refill.
One of the first things you may notice is that the "flapper" may be messed up. That's the tiny rubber item where the water streams through the bowl from the tank above. Verify that the flapper is either damaged or permanently ruined. If it is broken or damaged somehow, you can easily replace it.
There are some other elements that could take a few small repairs, including the arm that maintains the float in the correct position to fill the tank. Again, this can be fixed using these few simple tools and it's a good example of the kind of amateur plumbing that often does not require a professional plumber.
One thing that you may find when inspecting toilets is that someone has been experimenting with reduced water flow. Sometimes putting an item into the tank can lower the amount of water used with each flush but it may also conflict with some of the workings of the various parts. More commonly, the parts are just worn, and simple replacement is the best option. Once you have completed one of the tasks, the process will become second nature to you.
All of this is just part of what you may experience when looking into the toilet tank in your home's bathroom. In general, your knowledge of the parts of your toilet will help you with upkeep from time to time. Remember, the most important factor in keeping your toilet tank interior working properly is making sure that nothing is obstructing the float arm and flap process, and that none of these parts is throwing a "weak link" into the mix.