use onclick event in option tag and call javascript function window.open("page name","_blank/_self","properties like height,width etc")
example:
<select>
<option></option>
<option onClick="Window.Open('MyPage.aspx','_Blank','widht=500px,height=500px')">Belarusian</option>
<option onClick="Window.Open('MyPage.aspx','_Blank','widht=500px,height=500px')">bulgarian</option>
<option onClick="Window.Open('MyPage.aspx','_Blank','widht=500px,height=500px')">German</option>
<option onClick="Window.Open('MyPage.aspx','_Blank','widht=500px,height=500px')">English</option>
</select>