Perhaps we ought to piyure this as a process, a methodology of steps.
No different than, say, finding ways to put cargo on a steamboat, you need a "bag of tricks" to use.
The first of those needs is a place that hosts--or stores--photos that is on line. This could be PhotoBucket, Picassa, Google Photo, or the like.
Next, you need some words for your post (unless you are our perennial laconic raider-hall ).
Next, you want your photo hosting alos open in another window on the computer.
Select the image you want. Typically you can right-click that image (some hosts have a "Share image" button or tab. If there is not a button, you typically want "Copi Image Location" os suc h similar If there is a button, it will typically show someting "http:\\ahkjdshf" or similar gobbledegook. Highlight that, and press CTRL+C (Copy).
Go back to your post, click on the mountain on the tool bar (It's the 5th one along from the left, bottom row of icons)
It will open up a window. In the "Source" box click CTRL+V (Paste) to copy your link. Press Ok (you can monkey about with text descriptions and image sizes, but it's under-productive at this point).
Your image ought to be visible.
For this image, I went to Google Photos, and used "Copt Image Location"
For this image, I went to Google Images, used "Model steamboats" and picked an image. I used "Copy Image Location" then used CTRL+V in the Insert Image box here
Ok, I did not like the image size, so I used the edit function. And I reset the width (only) to 500 pixels. (I guessed this number, 700, and & 600 were too big.)
Here's another I found on google images
Note that I set this to a 500 pixel width so that it would compise with the other two (that, and the detail is incredible).
Any of this help any?