You can change wall colour etc to 'interior design' your home or extension.
You will notice I have put a page linking to it on this website and if you get good at it you could print out your efforts to show me what you require for your projects. A fun easy way to decide what you want and convey your brief to me!
On the other hand if you hate tinkering with computers - don't panic I've managed for years with out it! :-)