Always a problem translating Chineese into english.
Basically everything that mooves needs to be lubed.
However because a mower works in such a dusty enviroment, this lube needs to be dry so it does not pick up dirt and becone a grinding paste.
So I always use white lithium grease.
Get the joint to open up as far as it will and push the plastic tube on the can as hard agains the joint as possible so you blast the grease into the crevases.
Don't be stingy. I get about 10 to 15 mowers out of a can.
Cables get treated to Tri-Lube which comes from a push bike shop for lubing gear change cables.
Again not cheap but a tiny 2oz bottle lasts about 2 years & I do well over 50 motorcycle each year.
The steering pins ( bits that rotate to allow the wheels to go left & right are generally a plain bush and need to be greased .
So there should be a grease nipple there.
The wheels themselves ( oft refferred to as rims) generally have a grease nipple that leaks like a seive to grease the front axels so I take the wheel off to grease the axel.
Most now days use a sealed ball bering so greasing does little apart from filling the void with grease to prevent water ingression, thus a wipe of grease will be fine to prevent rust.
The rear wheels need to come off at least every 2 years and a thin wipe of grease applied to the axels, to prevent them rusting solid onto the axel shafts.
If you want to use this mower for more than 3 years pay particular attention the all the steering linkages as in order to make the mower as cheap as possible there are no proper tie rod ends used anywhere so all the holes in the steering linkages will flog out oval in a season or two.
Pay attention to the bush at the bottom of the steering wheel shaft, hard to get at, rarely lubed and expensive to replace ( because it is hard to get at).
Don't forget the vari drive linkages under the seat and the brake .
Keep the WD 40 for your cars distributor, tools that you leave out overnight, testing for intake leaks and light penetrating duties.
It is not and never has been a lubricant. It is a good wetting agent and penetrant so gets into dry joints to free them up so they start moving again, then evaporates completely thus requiring more WD 40.
The bushes on the steering pins may well be nylon . WD 40 attacks nylon and makes it swell , which is why you never put it on any control cable, just in case the cable has a nylon linner.
I drain the fuel tank remove the battery & deck then stand the mower on its bum to do the underside lubing, it is a lot easier, faster and you will not miss anything doing it this way.
While up in the air get your leaf blower and blast all the accumulated debris from under the chassis. Compressed air and a long duster gun is a lot better if you have a home compressor.