I have problem whit glass

Can someone tell me why my glass looks like this http://failiem.lv/g/tgptexr#aa/1.png
My glass bottle dosent have such shape and its making up some shapes. What am i doing wrong ?

You did not supply a .blend file for us to check, therefore all of the following is guesswork.

Looks like flipped normals on the bottle. Tab into Edit mode, A to select all, W > Remove Doubles and then Ctrl-N to recalculate the normals.

You’re using smooth shading on a very very low poly model with “tall” (elongated) polygons = Blender is trying to smooth out a 90 degree angle over a significant portion of the surface, which will result in shading errors. Try using an Edge Split modifier or Autosmooth with a low angle (30° or so).

All the above refers to the bottle screenshots. Can’t see anything wrong with the cube on the small image, sorry!

Or add additional edgeloops close to each major turn where you want a relatively sharp corner.