What you are doing is the highly illegal practice of hot-linking. You're illegally taking the image address off somebody else's web server/site & illegally posting the image at another site using img tags. You're stealing the image & their bandwidth off their web server. It may have been your image, but it's their server carrying & serving the image. You can't legally hotlink to the image in most countries without the webserver or site's permission. You should save the image on your computer as jpg, or convert it to jpg of a proper web size & file size. Then upload it to our site or an image server.
When posting at stories, or here, you'll see a place to upload attachments below the box of your text. If you don't see it, you may have set up something wrong in your member profile to hide it when you joined. Go to your member profile, & set it to un-hide the attachments option.
They can be jpg or gif up to 700 pixels wide, & 600 pixels high. Each image can be up to 60kb in file size. You can post up to 6 pictures per post (if you press on more attachments). However the total of all the pictures in a single post can't exceed 120kb. So if you post 6 in a single post, each one could only average 20kb. I get around that in our galleries by only posting a couple of the large pictures in a single post, but lots of smaller pix in another.
PNG is wastefull. Use free Irfanview to shrink or compress your images to jpg. You can also brighten or sharpen with it.
http://www.irfanview.com/I use my own homemade imaging & video software to manipulate media. But Irfanview is probably the best, easiest to use, & it's free. Play around with a couple disposable images first to get used to it & experiment. You won't be able to post 250-500mb PNGs at most forums & privately/independently owned sites.
Don't hotlink. That's where you post the image URL from another site directly into your post. The source of the image can usually track it to us, & send me a nasty letter for hotlinking to their images off their server. When you upload an image to our site from your computer, our own servers serve the image instead of theirs. We carry the image for you right here at Betty's. We are our own image servers -- a rather impressive expensive array of 4 hybrid cloud servers.
You can upload images directly to all Betty's sites since 2002. Even on our old Starblvd hosts for stories long before that, you could upload pictures too. But currently all our sites use the same modified cores, all on their own servers. So all our sites will accept jpg & gif uploads into posts.