A few quick and easy steps of a photoshop tutorial on how to make snow and flakes in photoshop
Step 1: Open Up the Picture in Which You Want to Create Snow As Well As Open a New Document and a New Layer in Photoshop
Step 2: On Layer 1 Make a Circle Using Marquee Tool and Then Go to Background Layer and Click Control+i .This Will Fill the Circle With Black. in the Same Way Make Different Sized Circles.
Step 3: Now Save This Brush by Going to Edit>define Brush Presets
Step 4: Now Open the Image to Be Edited, Create a New Layer and Draw Snowflakes With the Brush You Made. After That Blur Them a Little With the Help of Gaussian Blur.
Step 5: Now to Create Snow in the Background
Go to select>color range. Select sampled colors and increase the fuzziness to about 150.
Step 6: This Will Select Some of the Areas.
Now create a layer mask on this layers copy. Adjust its lightness to almost 100 %. You're done