You have two options for uploading your app: 1) you can publish your app to the App Inventor Gallery, or 2) you can upload your app's .aia file to Google Drive, Dropbox, etc. If your app uses an extension, you must use the second option because the Gallery does not allow extensions.
- App Inventor Gallery: follow these instructions to publish your app to the Gallery
- Shareable Link: from your app, click Projects > Export Selected Project to My Computer. This will download an .aia file to your computer. Upload your .aia file to a file sharing platform of your choice (Google Drive, Dropbox, etc). Be sure to make the link publicly accessible.