Any photo of the RH side shows the area.
To access the filler hole, you remove the plastic pin on the little rectangular panel on the RH cowl (above the cylinder head cut-out) and swivel it away (it has a tab at the RH end of it).
You the LIFT the LH side of the silver plastic cover and when it pops off the plastic pin, you slide it to the right to remove it. The oil cap is then visible. You need a small funnel to fit the little filler hole. You can see examples in the oil threads.
Reinstall is the reverse, of course.
Have the bike on the centre stand and be careful of over-filling.