<fieldset>
    <legend>Grup 1</legend>
    <input type="radio" name="radio_btn1" id="naber" value="naber" /><label for="naber">Naber</label><br />
    <input type="radio" name="radio_btn1" id="merhaba" value="merhaba"  /><label for="merhaba">Merhaba</label><br />
    <input type="radio" name="radio_btn1" id="selam" value="selam" /><label for="selam">Selam</label><br />
</fieldset>
<fieldset>
    <legend>Grup 2</legend>
    <input type="radio" name="radio_btn2" id="naber1" value="naber1" /><label for="naber1">Naber 1</label><br />
    <input type="radio" name="radio_btn2" id="merhaba1" value="merhaba1"  /><label for="merhaba1">Merhaba 1</label><br />
    <input type="radio" name="radio_btn2" id="selam1" value="selam1" /><label for="selam1">Selam 1</label><br />
</fieldset>