Photoshop is quite the behemoth application, and if you are new to working with it, it can be a bit overwhelming knowing where to start. If you are new to working with Photoshop and wondering how to get started, check out this fantastic video tutorial that will show you the first tools you should learn and how to use them to work on your photos.
Coming to you from Nick Page, this excellent video tutorial will show you the first tools you should learn in Photoshop and how to use them on your images. By far, I think the first thing every photographer should learn about is layers. The beauty of layers is that they allow you to edit images nondestructively (without irreversibly altering the original photo). They are the fundamental base of just about everything you will ever do in Photoshop, and they go a lot deeper than simply being blank palettes on which to add adjustments or alterations. You can change how they interact with other layers via blending modes, or you can apply them locally using masks, which allows you to create targeted adjustments on specific areas of your images. Check out the video above for the full rundown from Page.