Heroku deployment

am trying to deploy an app on Heroku but evrytime i try to deploy am getting this error?

! No default language could be detected for this app.
HINT: This occurs when Heroku cannot detect the buildpack to use for this application automatically.
See Buildpacks | Heroku Dev Center
! Push failed

Hello! There’s documentation on how to deploy an Elixir Phoenix application here: Deploying on Heroku — Phoenix v1.8.8

Have you followed all the steps there?

this is when am seeing it …wow let me read it

It will be that you can help me