I have 2008 Express Chevy Van,with power locks and power windows,can remotes be added to this truck to open locks?

If you have that kind of money yes. Im assuming you bought it used and if so first try calling the dealer with the VIN and ask if it came with a factory remote and maybe you just didn't get it from the previous owner.

You would have to get an aftermarket alarm installed and they aren't very expensive all the way up to quite expensive. Make sure its installed by a reputable shop.