title: altering QueryString parameters / values
body: <p>I would like to better understand the issue of setting new parameters to a url 
  and retrieve it via</p>
  
  <p><code>var ParaValue = Request.QueryString["parameterName"];</code></p>
  
  <p>so if I have a URL :  "http://www.myWebsite.aspx?UserName=Alice"</p>
  
  <p>I will retrieve it via example above </p>
  
  <p><code>string uName = Request.QueryString["UserName"].ToString();</code></p>
  
  <p>but what if I want to alter value e.g. make UserName = "Ralf"</p>
  
  <ul>
  <li>Re Edit</li>
  </ul>
  
  <p>when a button is pressed ,
  there is a parameter "state" that holds a reference to wich button was pressed 
  the value of state was = "none"
  now i want to set it to img_button1.</p>
  
  <p>i am not even sending the actuall imgbutton id </p>
  
  <p>i am hard coding it just for testing /referencing</p>
  
  <p>so i could know i am in the stage of event reaquested by the procidure of the given event of 
  button1 </p>
  
  <p>when event triggerd by <code>img_button2</code></p>
  
  <p>i whould then want  to set the state to "img_button2"
  etc'</p>