You can't tell by taking a photo of the mirrors.
You need to defocus a star and look at the patterns it displays. You should see a large white circle with a smaller black circle in the middle, with nice concentric rings going out from the edge of the black circle to the edge of the white circle.
Have a look at
this picture for an example, the image on the left is a telescope that is well collimated, the picture on the right is a telescope with poor collimation.