Congratulations on your new puppy! I have found in the past that if you get a few drops of the puppy's urine (or a tiny smudge of it's poo) on to the pad you want it to mess on the next time, then let the pup sniff at it, the pup will usually do its future poos on the pad. I have always started with that the very first day I got my pups. When they have done it on the pad, always reward them with a cuddle so that they know they have done good! NEVER ever chastise a puppy for getting it wrong as it will frighten them. Once the puppy is a bit older, you can start training it with a clicker. For advice visit
http://www.clickerzoneuk.co.uk/. I took my last pup to puppy classes (clicker training / Good Citizenship Awards) and we both had a fabulous fun time and I now have a wonderfully well behaved, happy and safe dog. Your vet will know where there are classes. As or who will be the top dog? Well, it is usually the older one, even if it may be the smaller.