Here is an excellent introduction to using Sharepoint Designer 2010 to customize your Sharepoint implementation:
Here is the third in a three part video series on how to organize your data in Sharepoint Online:
The following video is the second of a three part series on getting your files and folders (data) uploaded to Sharepoint Online:
I found this three part video series on Sharepoint Online presented by a Sharepoint MVP.
The audio is not great, but I think this series could be very helpful.
Here is part one of three: