To get your app key, browse to the Dropbox App Console. From there, create a new "Dropbox API app" or select an existing app. You'll find your app key there. Be sure to enter https://dbxoauth2.site44.com in the "OAuth 2 redirect URI" field.

Enter your app key into the text box below:

curl -X PUT https://api-content.dropbox.com/1/files_put/auto/hello.txt?overwrite=false \
     -H 'Authorization: Bearer ' \
     -H 'Content-Type: text/plain' \
     -d 'Hello, World!'