How To Convert PSD File To RGB Color Space As Recommended By Walgreens Photo Center PHOTOSHOP CC 2019 User
Hello
Can someone please help me with the following questions concerning the below image:

Q1) I saved the original image as a psd file. Then I saved an additional image as a JPEG file, because I want to have an online photo service print the image, and thought a jpeg image would be easier for them to print. When I tried to reopen it later, a photoshop message appeared telling me it could not be opened due to a program error. What did I do incorrectly?
Q2) After I went online to Walgreens, their online photo printing service recommended the following:
“If you are editing photos in a separate program such as Photoshop, save your images with a RGB color space to ensure their clarity and compatibility with our website.” Can you please instruct me how to save a PSD file as “a RGB color space?
Thank-you for taking the time out of your busy schedule to assist me.
Newbie Me
