when you go into the edit screen select enhance, then lighting, then levels. When the levels screen appears click on the channels selector. Select red and move the left slider over on the histogram until it just touches the black on the histogram. Do the same with the right slider. Do not worry about the changes in your picture. Now select the green channel and do the same. Finally do the same with the blue channel. It should balance the lighting in your picture but will not remove the yellow cast. Click OK.

Now select enhance again and choose adjust color then remove color cast. An eye dropper will apear as your cursor. Find a neutral area in your picture and click it with the dropper. The picture will change color. If it is not what you want select reset and find another spot. Try to find an area that is suppose to be white, black or grey. This will remove the color cast and the owl should be white. Then you can continue with any other editing you want to do. When you are finfished save the picture. Try and accomplish all of your editing at once. Since you are working with a JPEG the more you save the image the poorer the resolution will become. Hope this helps a little.

Don't be afraid to play with any of the editing features to see what they do. As long as you don't save anything you won't hurt your picture.

All DX lenses can be used on the D5100. Non-DX lenses can also be used on it, they will all fiy and meter. The problem comes in the fact that the D5100 does not have an AF drive motor in the body so for a lens to autofocus on the D5100 it needs to be and AF-S type lens that has the AF motor in the lens. Non AF-S lenses (DX or not) will have to be focused manually on all D40, D60, D3000, D3100, D5000 and D5100 models. AF-S AND non AF-S lenses will all AF on any other Nikon DSLR body as they all have an AF drive motor incorporated into the body.
Hope this helps.