There's no requirement for a manual! - just read the labels on the sockets!.
Essentially there are a number of possibilities!.
1) DVD player with inbuilt decoder and amplifiers, connect speakers to this.
2) DVD player with inbuilt decoder, but NO amplifier, connect the six phono outputs to your six channel amplifier.
3) DVD player with NO inbuilt decoder, but with optical (or coaxial) digital output - connect this to the digital input of your external Dolby 5.1 decoder and six channel amplifier.
4) DVD player with NO inbuilt decoder, and NO digital outout - you can't get Dolby 5.1 from this.
In all cases, it's obvious what you've got, the sockets are labeled on the back!.