CardDAV is one of the standards that can be used to keep contact databases in sync. I didn't realize Yahoo used that standard, but you should be able to enter you Yahoo password there for it to work. Normally you wouldn't have to, but since your account seems to be going to Yahoo indirectly, maybe you do.
It may not work, in which case I have no idea how to make it work.
You should probably remove your attachment and use something to blank out your email address before posting it again. Skitch is free and easy to use for this kind of thing.