How do i fix and y am i walking on the sides of my feet?

Check your shoes: See if your shoes are wore out unevenly and they cause your foot to slide over to the outsides. If you have a low arch and they flatten a lot an arch support added in shoes may help. If you have pain, have done these things with no relief, consider seeing a podiatrist.

See a doctor: You need to see a podiatrist to evaluate why you are walking on the sides of your feet. Once this is determined then treatment can be started.