Take him outside after he has been fed ...use a word that he will associate with "going" for example "Bombs away"!
If he doesn't go first time don't worry ..repeat the practice and he will soon get the message .When he does perform praise him,make a fuss of him and perhaps give him a little treat.
I am not a believer in these puppy pads and stuff ..as soon as they are old enough and able to go outside they can be toilet trained easily enough with a bit of patience. Get him into a routine of being put outside after meals ,last thing at night and first thing in the morning.