How can I relieve the pain on the bottom of my feet?

Depends. Depends on what is causing it. More info needs to be given. Since, you say feet, we know it is on both sides. So if I am throwing out a guess, i would say try arch supports you possibly have plantar fascitiis, but really more info is needed.
See a doctor. You need to know the cause of the pain before it can be treated. See a doctor for an exam and treatment.