I don't know how to play scrabble so can't catch the logic of the excercise.

All you need to know is, the Scrabble player has tiles, and each tile is a character. Later the player can use the tiles to form words and earn points.

In the hasTile(char tile) method, you want to find out if the player already has a tile with that character or not. You're almost there.

tiles.indexOf(tile) will check the string 'tiles' and return the index of the character 'tile' in the string. If 'tiles' does not contain this character at all, the method returns -1. So you just apply indexOf to the 'tiles' string, and check if the result is -1.

  public boolean hasTile(char tile) {
      // TODO: Determine if user has the tile passed in
      return tiles.indexOf(tile) != - 1  
  }

Or this works just as well, using the getter instead of directly using the variable name. Don't forget the brackets, because it's a method.

  public boolean hasTile(char tile) {
      // TODO: Determine if user has the tile passed in
      return getTiles().indexOf(tile) != - 1  
  }

This works in theory but is the wrong solution to the exercise because it adds unnecessary code. It does exactly the same thing than the above with more lines of code.

  public boolean hasTile(char tile) {
      // TODO: Determine if user has the tile passed in
      if (getTiles().indexOf(tile) != - 1) {
          return true;
       } else {
          return false;
       }
  }

In your case, the "hasTile =" that you added in the brackets causes a compiler error. You don't need it! tiles.indexOf(tile) != - 1 is a boolean expression. It is either true or false. You can return it directly without the need to put it in a variable or to add an if block.