Hi Sabrina!
You can do a few things.
To embed the photo inside the post, you will need the URL of the actual image location, not the link to the image on Flickr, etc. So right click on the image itself and choose "copy image location" and that will work.
Or you can click the paperclip and add it as an attachment from your hard drive as well - it's up to you!
Let me know if you have trouble and I can peek at the image and help!