With your new marble image the current one, select the deformation tool. This will put a frame, with square 'handles' at each corner and the centre of each side and a rotation handle in the centre, around your whole image. Place your cursor on the handle at the top left corner, and hold down CTRL. The cursor will then look like this.

Still holding CTRL down, left click and drag towards the right. Release the CTRL key and the mouse button and check the figures on the status bar. You need them to read 124,0 when the cursor is on the corner handle. It does not matter if the second figure reads 2 or 4, but the first one needs to be 124. If the figure is higher, press CTRL again and click and drag left. If it is too low, move right. Always hold down the CTRL key while you are moving the cursor, so that the top right corner will mirror the top left. When you have it in the right position, go to the tool options panel and press apply. Your marble now looks like the image below.

In the illustrations which follow, I have this marble image zoomed out to 1:2 in order to keep the tutorial illustrations small. If you find working in a small size image difficult, you can zoom the image to 1:1.

Now press the deformation tool again and place your cursor on the handle at centre bottom of your image. Left click and drag upwards till the second figure on the status bar shows 130. You will have to release the mouse button to check the readings. Apply the deformation at the tool options panel again. Now your marble looks like this.

Make your room image the current one, and on the layer palette click on Layer 1 so that is the current layer. Use Edit>Paste>as new layer. The marble will appear in your image. If it is showing behind the windows or any of the green is still showing, use the mover tool to adjust it into position. In the layer panel, it will appear as layer 3, immediately above layer 1. Right click on this layer, select rename from the menu, and rename it floor. Your room is now taking shape.

Now we are going to add a couple of steps at the back of the room. If you have used the clipboard for anything else since you did the floor (I am assuming that people may not do the tutorial all at once) then go to the floor layer, click on it to make it current, and use Edit>copy to put it on the clipboard again. If you are going straight from the floor to the steps it will still be on the clipboard.

In the layer palette, click on the top layer - back wall - to make it current, and then use Edit>Paste>as new layer. Another copy of the floor will appear across the middle of the image. It will not be easy to see where it ends and the floor starts, but we need it lighter anyway, so use Colours>Adjust>Brightness and Contrast. Set brightness to 15 and contrast to 0 and click OK. Go to the Layer Palette and rename this layer Step 1.

Use the mover tool to pull it to a position where it leaves about half of the floor uncovered. It will be covering the wall to a little way up the windows, and we need to cut off that part. The easiest way to do that is first to draw the slider of Step 1's layer in the layer palette back a little so it becomes semi transparent and you can see where the wall ends and the floor starts underneath it.

Now use the selection tool set to rectangle in the tool options palette, and make a rectangular selection that can start anywhere above the step marble, must be the full width of the image, and the bottom must be exactly on the line of the wall joining the floor.

Hit the delete key, and then put the Step 1 layer slider back to 100. Now select a narrow rectangular strip at the bottom of the step marble (about half a centimetre deep, and it does not matter if your selection rectangle goes beyond the bottom of the step marble) and use Colours>Adjust>Brightness and Contrast with brightness at -48 and contrast at 0. That will make the riser for your step.

Adding another step is simplicity itself. With Step 1 still the current layer, use Edit>Paste and Edit>copy>as new layer. Rename the new layer to Step 2, and bring it down till it is halfway across step 1. Make it semi-transparent as you did with the first one, select and delete what is above where step 1 joins the back wall, and put the layer slider back to 100.

On the final page I will show you how to add pillars, and give you a picture of another room so that you can see how you might add variations using these basic 'building blocks'.