I need to replace the battery?

I need to replace the battery - opened the battery cover behind the front passenger seat - it is not a typical nut and bolt cable leads on the battery. There is a nut that has to be unscrewed and then the clamp is somehow "attached" to the battery posts. Is there anything that I need to be aware of before I attempt to take the leads off of the post. I gave a small attempt, but it was getting dark and I didn't have portable lighting available - so I put everything back together. I have never seen anything like that.