It was easier than I thought because unlike some other manual transmission, our car has a dipstick to check the fluid level.
I almost had a heart attack when I finally checked it and noticed the level was away below low!
The drain plug is a little further back from the oil filter and engine oil drain plug and is rather large so you can't miss it.
Just undo it (you'll probably want a breaker bar for this and other tough bolts) and let the oil drain into the pan.
I honestly couldn't see the fill plug too easily but I had access to a large funnel so me and civicless put the funnel into the dipstick and slowly filled it from there.
After putting in some Royal Purple 75W90 which practically cost my arms and legs.......the car drives and shifts so much nicer.
*Update - the manual says it takes 4.0 litres for the transmission
There was not much difference in adding oil between the low level and above high level, so be aware of this and know exactly how much oil is going in there to avoid an overspill.