Completed newbie, starting from Apple TV 5.0

I apologise for my complete lack of knowledge. I have just bought a Apple TV 2 which is on firmware 5.0. 

From what I have read you can jailbreak all versions up to 5.3. What I can't understand is whether it is possible to upgrade to version 5.3 and then jailbreak, or whether I just have to jailbreak straight from version 5.0. My end game is I want to get Nito TV and XBMC on the device. I like the idea of the 5.3 untehered jailbreak, hence my desire to upgrade to v5.3 before jailbreaking, but is this even possible?

If someone could advise the best course of action for me to take, and link me any help on the subject I'd really appreciate it

Thanks!

Just get the latest version of Seasonpass from this site and choose the 5.3 download.  

It will jailbreak your ATV over the top of your 5.0 version.  With just a little reading or YouTube viewing, you should have no issues handling this.

You can google how to find the Nito Installer which is simple to use with your jailbroken Apple TV.  Just make sure your ATV and computer (XBMC is installed wirelessly) are on the same network when you try to install.

Good luck!