You really need to try and focus on something quite large close by which will allow you to get "something" in your eyepiece which you can focus on.
Don't you have a big tree or something similar only a couple of hundred metres away?
Maybe a telegraph or light pole?
Then you adjust the finder scope to bring the same object into the centre of the finder scope's field of view. Then your scope and finder will be aligned
Sorry, but that's about all I can suggest.
Slew the scope around until you see something enter the bright "white field". Then try turning the focus knob all the way in each direction.
If none of this works, we might have to consider the possibility your optics (mirrors) are not aligned. This points toward a topic known as collimation. We'll cross that bridge when we have to.