All are mainly rear of the tank plants.
Amazon Sword - Plant toward the rear off set from centre slightly or toward a corner. Should have a bulb at the base, snip any dead roots off and leave about an inch or so of white healthy roots. Create a hole and place the bulb in, close off the hole with substrate then pull the bulb upward slightly so the bulb is sitting a few mm above the substrate. Tugging up will also make the roots face down and thus grow that way.
Cabomba - Plant again toward the rear, prefereably the corners as this will grow TALL, and rather fast. Plant each stem a few cm apart so the ower leaves recieve light, otherwise it'll grow leggy and the lower stems will be bare and ugly. This require regular pruning and replanting because it will easily grow over a metre long from base to tip and your tank isnt going to be a metre deep.
Vallisneria - Again a tall back of the tank plant. Separate the plantlets into individual bulbs, you'll find one pot can often make anything up 7 plants. So split them apart and plant much in the same way as the Amazon Sword. Plant them in groups toward the rear or corners and they'll spread into often dense clumps of grassy weeds. Might require pruning every so often to remove some of the plantlets as it can quickly take over and create to dense a clump.