Please prompt me how to make the program better.

I write a test task for employment.
In general I consider that I coped with a task but since I am self-educated programmer ( higher education - physics).
the program,PERHAPS, works not rather well, or simply in a code there can be dirty places.
I ask for suggestions of skilled programmers, what is necessary to complete in the program for proper result.

Requirements to a test task:
"Your task is to create a windows standalone application that will load and properly render cat-model with diffuse + normal maps and with 3 omni lights rotating around it.
Also user should have functionality to rotate and zoom camera.

For rendering you should use OpenGL, and preferable GLSL for shaders"

Program link:
Main part of code:

or if it is a problem to run the program at last watch the video,pleas: