Insert Where condition in dynamic generate query in ASP.Net

Hi,

How to insert Where condition in dynamic query

int EId = Convert.ToInt32(Session["EId"]);
string displayCName = coun[0].DisplayCName;
string valueCName = coun[0].ValueCName;
// Generate dynamic query.
string query = "SELECT " + displayCName + " AS Text," + valueCName + " AS Value FROM " + fromTable;

In above line code i am going to insert where condition 

Ex:select EId,EName from Employee where EId=EId

Could you please help me

how can i add where condition in  below line of code

string query = "SELECT " + displayCName + " AS Text," + valueCName + " AS Value FROM " + fromTable;

Could you please help me