If you have registered your party at meetup.com (see the list of registered parties here) you will be receiving an email with a username and password for this site. Use an official WordPress mobile app to login to wp10.wordpress.net with the supplied username and password, and post your photos from there. Piece of cake!
Click on the link to download the appropriate app for your mobile device:
- WordPress for iOS – Download
- WordPress for Android – Download
- WordPress for BlackBerry – Download
- WordPress for Windows Phone – Download
- WordPress for Nokia – Download