Writing net 2.0 code ?

Question

Suppose I have net 4.0 code:

 

var node = new TreeNode(rootDirectory["Name"].ToString()) { Tag = rootDirectory };

 

I want to learn how to write net code 2.0 statement above how to rewrite ? Do you have a software name that converts net 2.0 code to net 4.0 or vice versa for ease of code lookup ?