I have recently bought a bluetooth keyboard for my galaxy tab s 10.5 on ebay. There was no user manual and unfortunately I cant find one on Samsung's website.
Just turn on the keyboard, then on your device bluetooth on and scan for devices. Bluetooth has an effective range of 10-15m, so chances are you won't see any other devices anyway. Connect to the keyboard and you're good to go.
I put the manual on Mega at https://mega.nz/#!NFgnWIgJ!IqGdR3Ao2..._iHpKFk5wVSJJA (Page 5 gives the connection instructions. It's simple - if the keyboard is on and the phone isn't pairing with it, press the keyboard's Bluetooth button for more than 3 seconds.)