To upload a file, you can go to community/group/buddy Wall or Files service, and then tap the Create button to start uploading a new file.
For iOS users, to upload a file, you need to select file from the Cloud Storage Service (e.g., Dropbox, Google Drive) in your iOS device.
For Android users, to upload a file, you can select to upload from device local file management or from Cloud Storage Service (e.g., Dropbox, Google Drive).