Need a little guidance

[MATTYZ426F]

Noticed that it seems left side is lagging and as I was greasing all locations and looking for fitting on rear I noticed oil on inside of rim.
Wheel bearing? Wheel seal? Is this a easy repair? I'm mechanical inclined but not a mechanic but I can get by.
Any advice is appreciated.
2002 case 75xt

 

[foton]

check your chain case oil level,that might be where it is coming from if it low on the side that is leaking.