Are you using the Laser or the CNC?
I haven’t used them much, but you can import images you download from the internet. SVG files are best, but other images work too. You’ll want to examine the toolpath that Luban generates to make sure it’s doing what you think it should be doing. Too many images online have nearly-white backgrounds which can cause problems. Basic black and white images are best to start with until you get more experience.
There are also plenty of free tools online that let you create images. There are several posts in the forums about various tools. I found this one searching for “online tools”.