chandu,

Have you read the WWW::Mechanize documentation? If you are looking to submit a form which has a set the radio button to the value you want:

$mech->submit_form(
    form_number => 1,
    fields      => {
        #Radio button name | Value
        myRadioButton    => 'myRadioButton_Value',
    }
);
[download]

If you do not know the name of the radio button or the value you may want to investigate the $mech->set_visible method. If you are having problems please provide your code, the example html and the errors generated. If this post is also yours please read the links I provided

Hope this helps..

Martin