As you may have read in that link, XNA now supports 2 very different profiles, "Reach" and "HiDef". HiDef is the default, and requires a graphics card that supports DirectX 10 and a host of other features in the GPU (a full comparison can be found
here). HiDef is primarily for high-end PC and Xbox 360 games. Reach is for Windows Phone 7, and other games that do not use high-end 3D graphics. Reach mode primarily exists to remove unsupported GPU features for projects that will be targeting WP7, or to expand the potential playerbase of PC games that don't require the extra 3D power.
If you are developing on something like a laptop, it is likely that you cannot support the HiDef profile. You are more than welcome to code in it on your laptop, or low-end desktop, but you will have to test on the Xbox 360 or a more powerful PC. If you are just getting started out, it will be a long time before you will be able to take advantage of HiDef mode, and you will be working in 2D in Reach mode for a while.
To change to Reach profile, right-click your solution in the Solution Explorer, and select Properties. Make sure the "XNA Game Studio" tab is selected, and then choose which profile you want to work in.