How to integrate a graphql api in both backend and frontend using datahub config?

After going through all these documentations,

has installed datahub and enable it in the extensions.
And tried writing a sample query in graphql in the datahub config window in the iframe tab.
Up to here i am done but usually as rest apis are build in the action and called.How to do for this graphql?

If their is any documentation please recommend!

Thank you