Flattening Ground for Beginners

Next on my list is building a mine. The game refuses this.
First because the ground wasn't enough paved. Now the whole area is paved.
Now the game just refuses to build the mine with no error message.
I assume it's because the ground is not flat enough. So hence my question: for beginners: how do I go about flattening the ground.
Obviously I can dig dirt. And with some right and left clicking I can drop dirt. Either one drop, level all corners or drop all.
BUT I have serious problems seeing where there is a corner. Where there even is a tile, so it doesn't really work for me.
I'm using Latika's client. Does that even work with flattening ground?
I see some nice pictures in forum where other people can see a grid, and info about ground highs in the grid. I have no such thing.
Tips are much appreciated, thanks.
First because the ground wasn't enough paved. Now the whole area is paved.
Now the game just refuses to build the mine with no error message.
I assume it's because the ground is not flat enough. So hence my question: for beginners: how do I go about flattening the ground.
Obviously I can dig dirt. And with some right and left clicking I can drop dirt. Either one drop, level all corners or drop all.
BUT I have serious problems seeing where there is a corner. Where there even is a tile, so it doesn't really work for me.
I'm using Latika's client. Does that even work with flattening ground?
I see some nice pictures in forum where other people can see a grid, and info about ground highs in the grid. I have no such thing.
Tips are much appreciated, thanks.