Open up your PicsArt and click the + sign at the bottom.

Once you click it, some options will show up at the bottom. Click the edit button

Once you get there all your pictures will be there. If you want a specific kind of background then you can click something from your camera roll, but I clicked the back ground button.

I picked a any color,  it you can choose a different color if y'all want. Once yo you choose your color, go to tools. Click crop and you should crop it to, 512x800.

Once you did that you get your PNG and add it anywhere you'd like. I chose this PNG. ⬇️⬇️

And after this you can do whatever you'd like.

This is how mine ended up