Why color on the area near mouth and nose of my model is more dark? Cant change it and dont know what is it. Even when I add texture it is visible.
From looking at your screenshot, it seems that your normals are inconsistent. To fix this, Tab into edit mode, then select everything by pressing A twice,(assuming nothing is already selected in the scene) and press Ctrl + N to make your normals consistent.
You can usually tell if your normals have been flipped because the shading on your object will darken.