Yahoo mail problem

I have just opened my yahoo mail inbox to find that somebody has used my account to send a message to all my contacts. It reads:
My friend, http://sites.google.com/site/ftoftedhyh/4oyybbrs7c - it is check=
ed up (1mavvzobmz)=0A=0A=0A

This looks like a serious problem. I haven't opened the link.
Any ideas?

Ok. First Yahoo Mail is very spammy. I suggest Gmail.

1. Change your password its important.

2. The link is just a phishing site pharmacy.

3. Just send a email to all the contacts that someone hacked my account.

my attached file in mail got virus.
how to download it. its important.

plz suggest