Cephas, welcome to RetouchPRO

hope you enjoy your visits here..
There are many ways to do what you are asking and the following is just one way to get you started:
Ctrl+J (copy Background) UN-check the eyeball on the background layer (bottom layer) in the layers pallet
Ctrl+J (copy the copy) set mode to "Multiply"
At the bottom of the layers pallet there is an icon that is square with a white spot in the middle of it click on the icon (creates a mask, the white square in the layer you just created)..
Paint black with soft brush on the shadows at 20% opacity and 30% flow till shadows look OK (Adjust opacity as needed)(hold button down while painting to eliminate layering the paint,unless needed.. To correct mistakes paint with white)
Ctrl+A (select all), Shift+Ctrl+C (copy merged), Ctrl+V (Paste)
at bottom of levels pallet click the circle that is half black and half white.. select levels
Pull left slider till it is in the black of the histogram, move the center slider to the left till the picture looks OK
Shft+Ctrl+E (Merge Visible layers)
I Reduced size (Image>Image size) to 1024 at the largest dimension so "Neat Image" (found
here )would work
I used Neat Image at default to smooth the picture
I also used "Polaroid Dust and Scratch Remover" (found
here )Tile size(Minimum), Detect level 40, Mask size(minimum), feathering (centered)... Ran it TWICE.. Once with the Light dust Checked and once with it UN-checked (this reduces Light specks then reduces dark specks)
Enlarged image till just eyes showed selected just the Iris on both eyes using the polygonal lasso tool
selected the Dodge tool set at highlights and 100% with a brush size just larger than the selections clicked on each selection once
selected the Burn tool set at shadows and 80% clicked each Iris once
The picture should now be ready for further fine tunning like healing, cloning, levels, curves, coloring and sharpening
Hope this helps some