Summarize this article in one sentence.
Download the app from the App Store or Play Store. Tap “Sign up”, enter your name, email, and password, then tap “Create Account”. After signing up, you will be prompted to setup your computer if it is on hand. To do this, proceed to Dropbox (Computer) or press “Skip” to be taken directly to your Dropbox on your mobile device. This button appears along the bottom menu bar on iOS or by opening the menu in the upper left corner on Android. This button looks like the three horizontal dots and is in the upper right corner (iOS), or appears as a “+” icon in the lower right (Android). You will be prompted to enter a name for the folder. Tap “Create”, then tap and drag files to add them to the folder. Folders created on mobile will appear as a subfolder in the Dropbox folder on a computer. You will be prompted to browse your device for files to upload. You can also upload files to dropbox by opening the app (e.g. Photos) and tapping the “Share” button and choosing dropbox as the share method. Tap the Settings (gear icon) button on the bottom row (iOS) or in the options menu in the upper left (Android). Tap “Camera Uploads” to turn the feature on or off. This feature will automatically upload any photos taken with that device to your dropbox. Open the menu in the upper right (three vertical dots) and tap “Refresh”. This will force a sync and immediately fetch any files uploaded by another device using your account. iOS lacks this option and should refresh automatically. If you are having trouble, try restarting the Dropbox app.

Summary:
Sign up for Dropbox. Tap “Files”. Tap the options menu. Tap “Create Folder”. Tap “Upload file”. Enable automatic camera uploads (optional). Refresh your uploads (Android).