Clicking on buttons in strange emails is something which is most definitely NOT to be recommended!!
That email almost certainly wasn't genuine. Unless you were NAMED in the introduction (e.g. "Dear Harry Grove") it's almost certainly dodgy. (Never trust anything which starts "Dear member", "Dear customer, "Dear Yahoo user", etc).
By clicking that button you have, at the very least, told the sender that your email address (which was probably generated at random) is genuine. You might now find that you'll get hundreds of spam emails.
Far worse though is the possibility that you actually accepted something 'nasty' onto your computer. Run a full virus scan and then run any anti-malware software which you've got. If you've not got anything suitable, use the free version of this:
http://www.malwarebytes.org/mbam.php
Chris