If you've ever sent stuff off to be printed (like a print shop with paper products), you'll find they often want the format to be PDF.
It's a complicated affair to get started, but once you've done some editing you'll be able to convert image files (specifically JPG and PNG) into PDF files. You do this with Magick. Well, specifically with ImageMagick - which isn't quite accurate. You do it with convert and you get access to convert by installing ImageMagick.
linux-tips.us
Pay attention to this one. You may need to do some editing (I tell you how) for this command to work.
I'd say that this isn't something I'd suggest for an absolute newbie. They might be able to follow along. Meh... They won't break much if they try. They can always purge and try again.
It's a complicated affair to get started, but once you've done some editing you'll be able to convert image files (specifically JPG and PNG) into PDF files. You do this with Magick. Well, specifically with ImageMagick - which isn't quite accurate. You do it with convert and you get access to convert by installing ImageMagick.

Turn A JPG Into A PDF • Linux Tips
Today's article is an article that few folks are going to need, but those folks who do need to turn a JPG into a PDF will be happy with it.

Pay attention to this one. You may need to do some editing (I tell you how) for this command to work.
I'd say that this isn't something I'd suggest for an absolute newbie. They might be able to follow along. Meh... They won't break much if they try. They can always purge and try again.