Here is a GUI way to generate a new PGP key.
Open the Passwords and Keys (Seahorse) application
This screen will appear.
Either go to File
→ New
in the global menu or hit Ctrl + N
In the Create New ... window select PGP Key and hit Continue
Enter your full name and your email address, the comment is optional
Enter a strong password which you'll remember
Wait for the Generating key dialog to finish (this may take a while)
You're done!
You can find your key in the Passwords and Keys application's My Personal Keys tab.
Uploading your key to Launchpad is just a few clicks.
Go to Launchpad.net and log in
On your profile page click on the yellow edit button (a round button with a grey pencil icon) next to OpenPGP keys
Note: The URL to that page looks like this https://launchpad.net/~yourusername
Open the application Passwords and Keys (Seahorse)
Navigate to the My Personal Keys tab
Select your key and go to Remote
→ Sync and Publish Keys
in the global menu
Hit Sync
Note: The Sync button may be grayed out if no sync server is selected. In that case:
Hit the Key Servers button
Select the hkp://keyserver.ubuntu.com:XXXXX
key server from the Publish keys to list and hit close
Double click your PGP Key from the list on the My Personal Keys tab
In the key window that just appeared navigate to the Details tab, select the Fingerprint with your mouse and hit Ctrl + C
Paste the just copied fingerprint into the Fingerprint text field on the Change your OpenPGP keys page on Launchpad and hit Import Key
You're done!