c# - How to redirect to another page when selected dropdown item is changed? -

I have two dropdown lists that I am putting on this page. I can not work either:

  & lt;% = html.DropDownList ("CategoryId", Model category list, "Choose a category to see")%> (M = & gt; m.SearchExpression)%  

and

  & lt;% = Html.DropDownList ()  

I need something when one item is selected and I click on submit.

Use of & lt;% (Html. BeginForm ()) {%> & Lt;% = Html.DropDownListFor (m = & gt; m.SearchExpression% & gt; & lt; input type = "submit" value = "submit" /> & lt;%}% & gt;

You will have a controller with a poster action:

  [HTTP post] Public Actioncell Fu (...) {Return Direct Reaction (. ..); // or Redirect Reader (return) ..);}