Making a beach in Photoshop entirely from scratch is relatively easy to do. There are many variations to what your end result will look like, though a sky, sand, a horizon line and a large body of water will be common elements in all of them. While you may paint a beach using the paint brush tool, it's also possible to create the beach entirely from large blocks of colour fills and filters to give them texture.
Create a new, blank canvas in Photoshop. Do this by selecting "File < New" and adjusting your desired size settings.
Create a new layer, using the layer palette.
Fill the ocean in. Do this by first selecting a shade of blue for your ocean and then creating a large rectangular marquis and selecting the menu: "Edit < Fill" (choosing your blue foreground colour) in the dialogue window.
Create the sky. Do this by first creating a new layer underneath the ocean layer and selecting two colours in your colour picker for the sky colours. Choose a combination such as white and sky blue, or red and yellow for a sunset sky. Apply a cloud filter to your sky by choosing: "Filter < Render < Clouds." This will create clouds for your sky.
Create the sand for your beach. Do this by creating a new layer in the layer palette on top of your ocean layer. Select a colour for your sand such as yellow or tan. Use your paint brush tool and apply a series of brush strokes to create sand on top of where your ocean is. Fill in the area of sand using the paintbrush tool until you are satisfied with its appearance.
Texturise your sand by applying a noise filter to it. Do this by first selecting the yellow brush strokes created in Step 5 with the magic wand tool, then applying the noise filter by choosing the menu: "Filter < Noise < Add Noise." This will create a textured appearance and give your sand a more realistic look.
Apply the Dodge/Burn tool to various parts of your image to give it more depth and dimension in the form of highlights and shadows.
Adding in foreground elements such as a palm tree, beach umbrella, surfboard or boat will add more interest to your beach. Handpaint in waves to make your beach appear more realistic. Experiment with various Artistic filters to add texture and depth to your ocean, sky and sand. Each beach picture will be different, depending on your creativity and imagination.