I use Imgur -
https://imgur.com/ It's free to use.
For an image I either use the print screen button or the snipping tool. After I have my image I paste it in Paint. I save the paint image. I then go to my Imgur page and click new post. I browse to my image and select it. Hover above the upper right of your image and you'll see an arrow which opens a drop-down menu. From the drop-down menu select 'Get share links'. From there copy the BBCode (Forums) share option. Paste that in your post here and your image will show.