i want to make a login session for 20 minutes

if i wrote the following code, then it is giving the dafault value is 20

<pre id=code><font face=courier size=2 id=code>&lt;%
response.write("&lt;p&gt;"
response.write("Default Timeout is: " & Session.Timeout)
%&gt;</font id=code></pre id=code>

But my system is asking for login in an average 2 or 3 minutes.

so, what should i do?

Please help me.