Step 1:
The other side of this 30x60 cm paper is red. Fold over this line.

Step 6:
Press flat, see arrow.

Step 5:
Fold the upper edge just a little below the red edge, see arrow

Step 2:
Fold in half.

Step 4:
Press flat, see arrow.

Step 3:
Fold over the upper paper layer.

Step 10:
This is the other side.
Fold the edges to the left, the mountain-folds are prefolded lines.
Use glue or tape.

Step 8:
Prefold over these three lines along the edges.

Step 9:
Prefold in four parts of the same size, see arrow

Step 7:
Fold over this line.

Step 12:
Glue both edges together

Step 11:
Fold over these two lines, they are parallel to the other diagonal lines.

Step 14:
Fold these two edges towards each other, see arrows.

Step 13:
Make sharp folding lines on the four corners.

Step 15:
This is how the roof looks