Sculpt

Pick Sculpt in the tool column and five verbs appear in the strip under the view. Raise pulls the ground up. Lower pushes it down. Smooth softens what is already there. Flatten levels the area under the brush. Drag on the ground to use them.

Slope works between two points instead: click where the slope starts, then click where it ends, and the ground between them is graded from one to the other. That is how a road or a ramp gets an even climb.

Each stroke is one step of undo, so Ctrl+Z takes back the last one. Anything you placed on that ground keeps its footing, rising or sinking with the land.

Size, Strength and Falloff sit in the strip beside the verbs, and the circle under the pointer shows the brush. Size is how much ground the brush covers, Strength is how hard each stroke pushes, and Falloff is how quickly the effect fades towards the edge of the brush.

A high Strength with a tight Falloff makes sharp features. A low Strength with a wide Falloff is how you get hills that look like hills.

Press Advanced at the end of the strip and the panel on the right opens with a Shape grid for choosing the brush shape, a Slope range that limits the stroke to ground between two angles, a Jitter slider, and an Align to view toggle.

Slope range is the one worth learning early. Set it and a stroke only affects ground already within that range of steepness, which is how you carve a valley floor without dragging the cliffs down with it.