Hello,
I am working on tree stuff but i am very confused of Tree concepts and balanced trees , height of the tree.
What is an expression tree? how to create the expression trees.

Please request you to do the need.

An expression tree is a tree, not necessarily a binary tree, that holds the parts of an expression the same way a stack might hold them for prefix evaluation:

Expression:
2+(4*3)

Stack:
[+][2][*][4][3]

Expression Tree:
  +
 / \
2   *
   / \
  4   3

Look up how to convert infix notation to prefix notation and how to evaluate prefix notation using a stack. That is the first step toward understanding how expression trees work because they do the same thing.