Is there a way to change a materials opacity and transparency or do i have to import something
The answer you’ve been given so far is correct but seems a little incomplete in that it assumes you’re already rendering the object with a transparent shader.
You have to make sure that is the case - if you haven’t messed with the material at all, there’s a good chance it’s still using standard Diffuse. Go to the material first and change its shader to any of the shaders in the Transparent category. Try Transparent Diffuse for starters. It doesn’t have any new parameters or sliders to mess with, compared to the standard Diffuse shader, but that’s because its transparency is controlled by the alpha channel of the color you’re giving it. Click that and try to lower the alpha channel there. You’ll see your object fading out.
Change the alpha value of the material, either through a script or the shader itself.