Need help on installing speakers Octavia MK II

I'm planning to install rear speakers in my Octavia and need any advice you can give.
Since my Škoda wasn't equipped with rear speakers, there are some things that bother me:
Are there any wires already wired to rear speaker slots but just not connected or do I need to wire them from radio myself. If so, does someone have picture from where can i take output to wire it.
Do i need any special connectors, AMPs or anything like that?

As I never tried anything like that, I really don't know any details and sorry if something doesn't make sense, an actual guide of how to do all the wiring and such would be great if there is some topic like that.
Thanks in advance.