.sky files are XML.

Sometimes you might find it useful to look at the files using a text editor such as Notepad.
We have written an XML schema which describes what can be found in the file.
The latest version of that schema is here:
https://github.com/ProteoWizard/pwiz/blob/master/pwiz_tools/Skyline/TestUtil/Schemas/Skyline_Current.xsd

I am not sure what you mean about converting .raw files to .sky.
A Skyline document contains very different information from what you would find in a .raw file. Skyline documents contain a list of peptides and peak areas. A raw file contains mass spectra.

You can tell Skyline to extract chromatograms from a .raw file by using the "File > Import > Results" menu item in the Skyline user interface.

If you tell us more about what you are trying to accomplish we might be able to give you better advice.
-- Nick