Brake a case into components. Individual plank sheets

Hi All!! sorry for my English but im not native. In my job im using Solidworks to create a new model for a desktop. I want to create differents part to be able to send it to cut the wood the different plank sheets. I made a model in sketch and when they ask to join the bodys i deselect it. Now in Assembly i have a whole body and i cant separate into different parts. How can i do it or can you post some video of youtube where i can learn how to do it??

Thank you very much