I'd aim for these dimensions.
A square for your profile photo, one that crops circularly well is ideal. Then a super wide background because some people view things in full screen on desktop. You also want your background to look good on mobile though, so you kind of have to do something odd with the design like I did. These are the dimensions of my background.
Check out this app called Union. It will let you do a lot on mobile. https://www.pixiteapps.com/apps/union/
Thank you so much dude, you are the freaking man! I'll definitely keep that in mind about the background, but I'll check out that Union app right now and see what that's about! Thank you again, you are a huge blessing bro!
Basically, if you import my profile background that I attached above into Union as your Background, then you can start adding your own items into the Foreground one by one. You just have to flatten the image to the Background each time you are finished with positioning it. Eventually, you will have all of my designs covered up and your own custom design in the exact dimensions that you need for your background. There is even a mask feature to erase certain parts of your image. Lots of tools to explore and surely there are videos out there to help you learn. It used to be my go-to app when I did everything on my smartphone.
That is awesome! Talk about easy! Lol I am definitely going to be working on my profile this weekend, so I may have to give that a try! I'm kinda thinking about doing a collage of our family for my background, so I've been going through a bunch of mine and my girls pictures trying to find the good ones haha. I'll definitely let you know how it goes and I hope you guys have an awesome weekend!!