Help me please

 
public class BST
{ private BTNode<Integer> root;

  public BST()
  { root = null;
  }

  public boolean find(Integer i)
  { BTNode<Integer> n = root;
    boolean found = false;

    while (n!=null && !found)
    { int comp = i.compareTo(n.data);
      if (comp==0)
        found = true;
      else if (comp<0)
        n = n.left;
      else
        n = n.right;
	}

    return found;
  }

  public boolean insert(Integer i)
  { BTNode<Integer> parent = root, child = root;
    boolean goneLeft = false;

    while (child!=null && i.compareTo(child.data)!=0)
    { parent = child;
      if (i.compareTo(child.data)<0)
	  { child = child.left;
	    goneLeft = true;
	  }
	  else
	  { child = child.right;
	    goneLeft = false;
      }
	}

    if (child!=null)
      return false;  // number already present
    else
    { BTNode<Integer> leaf = new BTNode<Integer>(i);
      if (parent==null) // tree was empty
        root = leaf;
      else if (goneLeft)
        parent.left = leaf;
      else
        parent.right = leaf;
      return true;
    }
  }
    public int less(int n ) // return how many number are less than n appear in tree
  {
      if (root == null)
          return 0;
      int count;

      if (root.left == null) {
          return 1;
      }
      else
      count = 1;
      count += root.left.int less();
      return count;

  }
  public int nth(int n) // return the element that would be found at location n if the contents of the tree were stored in ascending order in an array; an exception of type NoSuchElementException should be thrown if such an element would not exist
  {
      return n;
  }
}

class BTNode<T>
{ T data;
  BTNode<T> left, right;

  BTNode(T o)
  { data = o; left = right = null;
  }
}