Okay so, you upload a photo to the website postimages.org
You choose picture size don't change and choose a photo from your smartphone / computer and upload it.
The photo is now to be seen in a small preview, if you click onto the photo it gets bigger.
Now, if you are on a smartphone you click on that photo again and hold your finger a bit longer on it, a sub menu should open. For computer you do a right click onto that photo. In that sub menu are a few options, you want the 5th one from above, something like "show picture".
The photo should now open in a new tab or with a new website adress. Now you click onto that new adress in the top. There should be a really long website name now. Something that starts with https and ends with jpg for example. You copy that exact adress.
If you want to put that picture onto this forum here you write this:
[ IMG width=300] here you put in the adress you just copied[/IMG]
But there are no spaces between the bracket,
this [ and the IMG] and at the end of the website link you need another bracket with a backslash [/IMG]
To make a photo smaller on this forum you need to write width=300 after the first IMG in the bracket
300 is just an example, maybe 400 will be okay too but I usually use 300
If you have any questions, let me know. I hope that all made sense, english isn't my first language.