first, you will have to place dispenser facing each other and place redstone lamp at the back like so.
place a fence between dispenser and put pressure plate at the top.
go behind to the left dispenser and place redstone comparator coming out from bottom dispenser and put repeater coming out from comparator.
connect redstone dust to bottom lamp
then, put in each piece of armor in each dispenser.
something like this (I'm sorry that I can't write things with mouse)
its done. when you walk up to pressure plate and after you hear something dispensed, you are all set.
you can see you have nice armor on you!