Run the Adobe Photoshop program and open the “File” menu. Choose “Open” and select the image to which you want to add the blur motion effect.
Create the background layer for your image. For that purpose, click on the image and drag it to the "New Layer" icon present in the layer tool box.
Now you can add motion effect to your picture, by clicking the “Motion” option in the “Blur” section. You can find the “Blur” section in the filters menu. This will completely blur the image. You can then add a layer mask over your image by selecting “Add Layer” from the layer tool box.
Choose the brush tool and set the unit to around 75. Also, select the black colour from the colour palette, appearing at the bottom on the tool box. The colour palette will only have black and white colours. You need to click on the black box.
Now you un-blur some portions of your image by clicking and holding the left mouse button and moving the brush tool over your desired areas. For instance, if you are editing a picture with your friend riding on a bicycle, then you may need to un-blur his face and some body parts.
Once you are done with creating motion blur effect, you can save a copy of your image. For that purpose, go to “File” menu and select “Save As”. Enter the name of the file in the “Name” field and select the output file type from the file type drop-down menu. Click “Save” to finish saving the image on your hard drive.