Agreed. You would probably have to start by explaining that there's important data, and that it is stored at a nanoscale. Then you would have to proceed to explain how they might get access to that data.

But that's not the whole of it. Once they can read the 0's and 1's, you need to tell them how to interpret them. So you need to provide (at least) an ASCII table in some extremely durable material.

The rest of the information (on how to interpret the data) can then be stored in the first mega/gigabytes of the binary data. Plain text ASCII only, ofcourse. No pictures, audio, or video. You could only include such data once you've told them how to build a computer and all necessary software.

I think you're better off storing a computer and a self-sufficient powersource in a vacuum, virtually indestructible structure. Has the added benefit that you can make cool movies about it :)