This involves several steps and builds upon the previous steps you just completed.
Find your GPG fingerprint. Replace youremail with the email address you used earlier to create your GPG key.
matthew@seymour:~$ gpg --fingerprint youremail
Something like this will be returned.
pub 2048R/38E0C789 2012-08-25 Key fingerprint = 6363 387F 7455 8929 E6E2 4619 4798 DFD9 38E0 C789uid Matthew Helmke <firstname.lastname@example.org>sub 2048R/BDE097FF 2012-08-25
Open https://launchpad.net/~/+editpgpkeys and copy the entire set of numbers and letter to the right of
Key fingerprint = into the text box on the web page. Click Import Key on the web page. This ...