Of course you can do URLs, but you can do it direct too.
You can upload direct, just takes a few extra steps...
Start typing on the quick reply, hit preview...
then click attachments and other options, and there is an attach option, click browse and it'll go to your computer file (my documents on my computer). Pick a file, then post. [They do just post in a row below your typing, but they are there.]
How's that Diane? Don't know if I could do more details, and I'm not very good at URLs.