Two Methods
Method 1 - Take a camera and find location where the light/sun is behind your subject. Focus on the bright background in order to darken the foreground/subject. Try a few different poses to create a distinct look.
Method 2 - Take an photo of your subject in front of a solid coloured back ground. Take a seperate photo of a background you would like to use.
Use Adobe Express or Photoshop to remove the background. Using photoshop, use the alt-left click trick to cut out your silhouette from black background.
Add your background photo to seperate layer.
Add another layer and add some sun, like the image below. Place the sun on the layer above your background and change the blend mode to "screen"
