layers in psp9

Hi i looked back and couldn't find exactly what i was looking for. i am new to this icon thing and right now i am in the basics, like just pictures but they come out really nice and sharp and everything. anway i was wondering, i was was reading tutorials about how to add differnet effects and they all have multiple layers but the thing is i have no idea how to add or change my layers. they just tell me to do it, not showing me or explaing step by step how to.

can someone please tell me exactly what to do - like step to step - on how to add or change layers and where to go. i am using psp 9. thanks!