Hi Kelly Rae and welcome to Dgrin
You can drag pics into the editor text box to upload and display pics on Dgrin. If they are already hosted on a web site (like SmugMug or Flickr) you can open the URL box for images that's on the editor toolbar and paste the URL. I think most of the people here use that method. The hosting site and gallery must allow external links.
Looking forward to seeing your work.
Its a pity you can't load pics direct from your pc as it would make life easier.
You can. Just drag a jpg into the comment box and it will upload to Dgrin.