When you first open the app, WeVideo shows you your media library, with videos, images, and audio files stored on your device. From here, you can easily drag items down to your timeline for editing.
By default, WeVideo shares to your WeVideo account in the cloud. You can also check options to save a local copy and share to YouTube. At the time of my testing, I couldn't get the Facebook share feature working, but I'm hoping the bug gets fixed in a future update.
WeVideo comes packed with 24 different themes for you to use in styling your videos. Unfortunately, though, you cannot customize them in any way from the mobile app.