A distracting background certainly spoils the beauty of a good photograph. With powerful image editing softwares like Adobe Photoshop, it is very easy to change the background of a photo. In this Photoshop tutorial, I will explain - how easily one can replace a distracting background with a desired background photo. I am using Adobe Photoshop version CS4 while creating this tutorial.
Step by Step tutorial – Change/replace a background image in Photoshop
Step 1: Open your image in Photoshop. Press ‘Q’ to quick mask and then select brush tool from the left toolbar. Paint the entire subject completely with the brush tool, ensuring that you don’t spread the color out of the picture. This process takes time. 
Step 2: Now after finishing painting the whole subject, press ‘Q’ again and select inverse from the drop-down menu of Adobe Photoshop. 
Step 3: After that, copy your image using Ctrl+C and open up the new background image in Photoshop itself by navigating through File –> Open. Paste this copied picture on this new background using Ctrl+V. To adjust the photo on this new background, press Ctrl+T (transformation tool). With this tool you can easily resize or rotate the picture on the new background, so that it looks a part of it 
Wasn’t that easy ? This is how you can change or replace a background image inPhotoshop. As an alternative, you can also choose to blur the background in Photoshop instead of replacing it with a newer one.