In a very general answer to your question, since the most basic Photoshop instruction is kind of outside the scope of the forum, may I suggest using the Photoshop Help menu, choosing Photoshop Online Help, then entering Crop into the search box. There's a wealth of information there, though at the moment the versions of Photoshop seem a bit jumbled up.
A specific answer to your question is to do this:
1. Open your image into Photoshop.
2. Choose the Crop Tool from the Tools panel.
3. Either drag a rectangle around the part you want to keep, or use the little rectangular handles around the edges to move the edges in. Move the edges around until you like the way the bright part, which indicates what will remain of your image after the crop, looks.
4. Press the checkmark near the top of the Photoshop main window in the options area to complete the crop.