The easiest way to post a picture is using the "Add image to post" button. It hosts you picture on imgbb. But you have no control over the picture afterward, you can't view it again or use it for another post or forum. Hopefully they're around for a long time and don't suddenly vanish with our pictures!!
A dedicated image hosting site is the the best way to store and refer to your pictures. Photobucket has been around for years and is easy to use. Unfortunately they changed their terms recently and now they will want $399 per year for 3rd party hosting, which is what you do when you post a picture in a forum from PhotoBucket. There are probably now millions of picture links broken in forums all over the world.
I use Google Photos to save my pictures but I haven't found a way to insert an image from them, only a link. Nobody wants to blindly click on links to view unknown pictures.
BUT!!! I found a way to insert pictures from DropBox!!
When in your DropBox, click on the "SHARE" button for the photo you want to share.
Then click "Create a link". A link is copied to the clipboard.
Then, in our forum, click on the "Insert Image" icon.
Paste the link from the clipboard.
NOW THE IMPORTANT PART! Change the end of the file name from ?dl=0 to ?raw=1.
In other news, I signed up with imgbb. Now that I'm logged into imgbb, when adding an image to a post the window opens to drop the picture into there is a small icon with 3 horizontal lines that when clicked shows my imgbb account. So, as long as I be sure I'm logged in, All the pictures I upload thru the forum will be accessible thru my imgbb account.
Does that mean they will be available forever?? I doubt it.
I found the best way to post a pic is to sign up for imgbb, log in, drag and drop, and drop the link into your post. That will get you the full size image and you will have later access to your pictures, vs. Using imgbb thru the forum.
I've been using IMGUR. I created an account, and when I copy the links, I've learned to add an "h" to the filename, plus the jpeg file extension. This shows as a perfect size for web forums -- not ginormous, and not thumbnail either.