How can I upload an image from my mac

I am trying to upload a picture .jpeg from my mac into my code, but it is not working at all. I am assuming this is possible, but challenging for a beginner? Thanks for some detailed help ahead of time.

you need to store the image somewhere online if you want to include it in a project

Would you be able to recommend a place or two on line to do this? Can it be free to do this or do you know? Thanks