Hey, cheer up, everyone has a first time. What you can do is experiment with those screenshot links and press Preview Post under your post instead of Submit Reply, that way you'll see the results of your posting above it without actually have posted it. Useful for seeing how the final result of your post would look like. Try it that way
Besides, you can edit your two posts there and insert the screenshots into them, trying as described above, so they become useful - no need to delete anything.