I had the exact same problem a while back (welcome btw)
Here's how I go about posting (I'm not good at explaining things, but I hope that I can help somewhat):
Step 1: Have the URL of the scans in question (I would recommend using photobucket or some picture sharing site to host them)
Step 2: Open up two browsers and have both of them open to daily scans (make sure that you are logged onto insane journal for at least one of them)
Step 3: On the browser that you are logged onto, look near the top of the page where you will see the word "Daily Scans" underlined as a link - click on it
Step 4: On the page that the link leads you to, look near the top of the page where there should be a little bar in the center with a bunch of little symbols - move your cursor over them, and one of them should say "post to daily scans" - click on this
Step 5: You should be directed to a little posting set up page - at this point, if you don't know how to use URL (like me) open up your other browser and click on the same "Daily Scans" link near the top of the page
Step 6: If you scroll down, you should find instructions for posting that show the code for putting pictures in - make sure that you do it under the cut
Step 7: Put the URL of the scans in question into the code, and post
Hope that helped - if not, just ask someone more intelligent and internet savvy than I