If you're serious about DIY you'll buy a used paper maintenance manual -
probably from someone on e-bay.
Do not buy a Haynes manual for it attempts to cover too many models and
so omits too much detail.
I'll email you, not the NG, valve adjustment instructions.
Oil changes are not difficult but can be messy. Oil is drained out the
bottom (drain plug) and the oil filter is inside the metal container on
the left rear of the engine that has two nuts clamping its cover. The
oil filter elements can be bought for on-line M-B parts houses. Use only
diesel grade oil; its designed to keep the soot in suspension. 7.5L is
the refill, change it after 5K miles.*