Just look it up on the internet, there are answers to lots of things. It would help you to get a better answer here if you gave name of the make of the bunk bed (if you can find a label or something...
I have a pdf if required for the assembly instruction s for Stompa Scorpio High sleeper - if required email me guymadgwick@aol.com
you can get them at nearly any bed store, ie dreams or online
To save space in bedrooms.
because the concept of bunk beds is that you are bunking with another person or even just another bed