Citroen c15d transmission oil amount needed?

Hi just need to know how much oil I need for a transmission oil change on my 2001 c15d . Also where is the filler hole.

I lost a lot of oil when I was changing a front suspension coil. The oil came out when I pushed the wheel hub down to refit the shock absorber. Is this normal or have I broken a seal or worse. It hasent leaked anymore since I replaced the shock but I haven't driven it anywhere until I replace the oil