We'll start with a "Box" (hotkey "X") with the values"Width"(X)=50cm, "Height"(Y)=5cm und "Depth"(Z)=50cm. You can insert those values directly via the "Numeric"-window (hotkey "n").

Now we'll divide the Box using the "Knife"-Tool (hotkey "K"). By rightklicking you can place several cuts without deselecting and selecting the tool every time you want to use it. By holding the "Ctrl"-key you can junction tools to an axis. Try it out.

Next we'll select thos four corner polys at the downside (see picture) and choose "Bevel" (hotkey "b"). With it you can pull out new polygons. Again with "Ctrl" you can junction your mouse movements; but not with an axis but to either "Shift" (Mouse up/down) or "Inset" (Mouse left/right). Again the Numeric-window comes in handy. For our chair we'll insert the values "Shif"t=40cm und "Inset"=0.

Well, so far we have a stool. But for turning it into a chair it needs a backrest. Like the legs, we'll pull it out of the box. Though we'll use "Smooth Shift" (hotkey "F") instead of "Bevel" ("b") this time. "Bevel" treats every Polygon individualy while "Smooth Shift" does not. Let's pull out the backrest 50cm. Of course the "Numeric"-window is available here also. The only interesting value for us is "Offset". "Sclae" and "Max Smoothing Angle" stay as they are. "Max Smoothing Angle" determins how big the angle between two polygons may be to detect a connection. Look in the manual for a better description.^^

Virtually we're finished but the chair looks very coarse and angular. That's why we push "Tab" to convert the polygons into subpatches to round the whole thing.

Now that looks quite nice but it's not exactly what we wanted. The legs have shortened and you can't sit on it anymore because your butt slides off. "Knife" ("k") in the following places can fix this.

The closer two points are in a subpatch-object the smaller the rounding will be... or something like that (see manual for a more detailed decription). This tutorial ends here. The result should look like this:

From here it's up to you to continue.Armrests can be pulled out of the sides, upholstery can be easyly beveled etc. etc.

3D is art, that's why experimenting is wanted! If something goes wrong there's always "Undo" (hotkey "u"/"Ctrl"+"z" for LW8) and "Redo" (hotkey "U"/no clue for LW8). "Learning by doing", some ambition and above all imagination are the keys to realize everything you want and that's simply fun.

Have a nice day! ;-)