Before you get into any sort of advanced adjustments or edits in Photoshop, you need to select the part of the image you are working on. Depending on the photo, this can be a tricky process, but luckily, Photoshop has a wide range of built-in tools for extracting specific parts of an image or creating layer masks. The Select and Mask workspace is the place to go for a lot of this work, and this excellent video tutorial will show you everything you need to know to use and get the most out of it.