Upload App on mediafire or another platform

How to update my app if my app its on .apk like sharing on mediafire or 4shared how to upload it ?
Because i dont have play store to upload/update it!

i- why would you need a play store account to upload an Apk file?
just upload the file and that’s it.

Make an update button within the application

But if in my app i put new menu or anything else but my client how to update it ? because my app its not on play store its on mediafire!