Step 1: open up your Photoshop and the picture you want to change the background colour.
Step 3: after that, at the top of photoshop click refine edge. here
this should pop up.
click the smart radius. after that adjust the radius. mess around with it. after you’ve finish click ok.
Step 5: After that simply click ok without doing anything. After you click ok. this will pop up.
Step 6: Choose any solid colour you want to fill your background. after you’ve finish click ok.
Step 7: you’re done! click ‘save’ or ‘save as’. make sure that you change the format into JPEG.