I have dry, itchy, cracked skin, and thickened heels on my feet. I have dark toenails & fungus for over twenty years. How can I get rid of this?

Evaluation. Sounds like you have a fungal infection. Would be good idea to be evaluated as there is medication available for all of these conditions. A physician may also need to perform a biopsy or culture as well.
Both easy and hard. it sounds like you have several things going on at the same time. Some of these conditions may be easy to address, while others more difficult. To get started, you will need to be seen by a physician to ensure that your general health and the treatment are compatible.