If your computer can't display shaders then there are two things you could try.
Firstly, updating the drivers on your graphics card. This can be done for free from the website of the manufacturer of your graphics card (www.nvidia.com
, etc). This might give you compatibility with shaders but chances are that either it won't or it'll run slowly enough.
Secondly, buying a new graphics card and more RAM for your computer. Although this would cost, it would be more likely to get you shader compatibility. I'm not an expert in these matters though so I'll leave it for someone with more knowledge of the subject if they want to explain further.