You can post and image using the image link. You screen capture, past into a paint program, and either upload the image using upload from computer option, or upload the image to Imgur.com and then past the url-link in the forum post.
Now regarding your problem.
Check your login details to ensure you are logged in.
In missing dependencies, right-click on the assets and choose download. This may download assets.
If these are DLC, this requires a bit more work so check these things first before we go to the next step.