A very simple question in as3.0

Hi there,
Im rather new in the as3 programming and i have a little problem with a simple img gallery hoping you may help me out…

i have a next and back btns and what i want is that for everytime that one of those btns is pressed, a different img will be loaded
so what im trying to figure out is how to attatch the counter value to the imgReqX format ? and again X represent the counter

var imgReq1:URLRequest = new URLRequest(“pic/back_stage/bs1.jpg”);
var imgReq2:URLRequest = new URLRequest(“pic/back_stage/bs2.jpg”);