how do I get the image URL and how do I see the image URL?

@zeropol thank you

If the image is on you computer, upload it somewhere ( imgur or discord or whatever ). Then, if Discord, you can "copy the image location" with right clic or long press if mobile. If imgur, they give you a link.

If the image is on a website : go on the website and do right clic -> copy image location ( or long press if mobile ). Depending on your browser, the sentence can be different, it can be something like "copy the image URL" or something like that. You can also "open the image in a new tab" and copy the URL in the adress bar if it is easier for you.
I hope you'll be able to add images to your posts