If you want to know how to colorsplash your photos on your computer, you can find a Photoshop tutorial for that here. If you don't have Photoshop, there is a free photo-editing software called Gimp. I never tried it before, but I saw a few videos and screenshots of it, and it has similar tools to Photoshop. If you have a mobile device, there are also apps that automatically colorsplash your photos if you tap on the parts of the photo you would like to be in color. :)
Have fun colorsplashing your photos!