The black background works in Yasmin's photos because of the backlight illuminating the hair. Yours doesn't have that.
I definitely wouldn't try changing the background completely. With the hair, it's just too difficult.
Do you mean the best way to send them?
Don't send them by email. Emails tend to shrink photos without your control.
The best way is to host them on a server somewhere and send the link to the client so they can download them.
There are a squillion ways to change the colour of items, and no two photos require the same method.
In this case I'd add a Solid Color layer of maroon colour, set to "Screen" blend mode, and mask it on very carefully.
Hang on ... I just realised you posted on the wrong instructions. Have you been FOLLOWING the wrong instructions????
You're supposed to be following these instructions: https://www.damiensymonds.net/cal_S5X_pc.html