ContentProvider and One to many relationship

Question

Java

There are tables User, Post, Content. The user has a lot of posts and the post has a lot of content.
The Post and Content tables have a field that is a foreign key and refers to the User and Post tables, respectively.
Thus, when creating a post, I specify the id of the user who created it. And when creating content, I specify the id of the post to which it belongs.
And here I don't understand how to implement the method:

@Override
    public Uri insert(Uri uri, ContentValues contentValues) {
}

And in that case, what would the Uri look like?