Once you have finished packaging your app, you can upload it to your PPA with the command:
dput ppa:myname/ppa myapp_0.1-0extras11.10.1_source.changes
NOTE: Make sure you build the source package with debuild -S. You can't upload a binary package.
Setup
If you don't have a PPA set up yet, you can create one in a few simple steps:
Login to Launchpad, or create a new account if you don't have one yet.
Activate your PPA on your profile page under the heading "Personal package archives".
Visit the page for your PPA for instructions on uploading or installing, and for a list of packages in your PPA.
Named Shortcut (optional)
You can also add an optional named shortcut for uploads, with a configuration file named .dput.cf in your home directory. This file looks like:
[myname-ppa] fqdn = ppa.launchpad.net method = ftp incoming = ~myname/ppa/ubuntu/ login = anonymous allow_unsigned_uploads = 0
With this config file, you'll be able to upload packages to your PPA using the shortcut 'myname-ppa' instead of remembering the full upload path for your PPA.
dput myname-ppa <packagename>_<version>_source.changes