Some things you need to get started are Google sketchup 8, and a computer. First you need to download it to your computer at Google sketchup 8.com. The first step is to open sketchup 8 and pick a template and get started.
Click use the square tool to make a square, then use push pull and pull the square up to as high as you want, but I suggest to type in 4’4’’. When you’re done with that you click on the pencil and make a line close to one edge but not all the way down. Now you draw a horizontal line, then you make the legs of the chair by using the square tool and make some rectangles and use push pull. Now you’re done.
If you want to you can use the paint bucket to make it look more like a chair. You can use this technique to make anything - buildings, cars anything you want. If you want somebody to be sitting in it, go to file 3D warehouse, get models, and type in anything and click on the one you want and click download now