In Saturate you can code data and memos (if it makes sense to treat your memos like data). While viewing some data (or a memo), simply select some text and use the coding tool to the left.
You can export all of the coding you've done as a collection of CSV files (which you can open in a spreadsheet application such as Excel). To do this you need to archive your project. Watch this video for more details.
For information about how to get an overview of all of the coding for a project, read about categorizing codes.