Please help with mf40 backhoe

[pbpimp06]

I am rather lost here on it it's a 70ish Massey mf40 backhoe and I do not have the slightest clue how to add or where to add fluid to the backhoe part of it it's got a pressure valve in the drum where the fluid goes but it's full looking and I know it's not full cause I've been changing leaking hoes on it so any help would be very much appreciated thanks Chris