Since you've identified yourself as a new birder then the best guide for you is the 6th edition (most current) of the National Geographic Guide to Birds of North America. If you know this is something you plan to do over the long haul keep track of the birds you see, a Life List, and the NGBNA is best because the descriptions and on one side of the facing page and the pictures are on the other side. The most important thing is to identify as many features of the bird as possible, color, beak, eyes, tail, feathers, etc. before you drop your binoculars to check the guide. The bird won't stick around for you to picture it and then hunt for the description. Not every guide has the picture and description so close together. Sibley's is good but not for a beginner, and the Peterson's Guide is not a user friendly set up.
I also carry a digital recorder so I can watch a bird and describe all the characteristics I see and then play it back later when my eye needs a rest. I use my monocular and spotting scope much more that way and I don't miss seeing too many birds. This summer I hope to add my 500th bird to my life list. Good luck.