<input type="radio" id="radio1" name="RadioGroup1" value="1" checked="true"/>

<input type="radio" id="radio2" name="RadioGroup1" value="2" />

<input type="radio" id="radio3" name="RadioGroup1" value="3" />

​

​

//in your jquery

var value = $("input[name=RadioGroup1]:checked").val();

​

alert("The user selected; " + value);