Lin:
You may be able to find dates by reading the hand-written info scratched into the relatively ungrooved portion of the disc between the labels and the playing surface: the pressing info was usually written there, to identify the record to the producer, before the labels (added relatively late in the process) were attached.

"Broad subset" is a maths term, but used (in this context) to mean a wide-ranging, not too specific, category. It's not computer jargon.

New Folder: if you use Windows, locate Windows Explorer (in Windows xP) or a similar window, listing all your directories. Later versions of Windows (there are plenty) may have renamed this: perhaps other contributors can help? Click 'File', then 'New', then 'Folder'. This appears, called 'New Folder', in the visible pane listing all the folders in that directory. While its name is still highlit, type in a new name for it. You can also achieve this by typing Alt-key & 'F' at the same time, then 'W', 'F' in succession. Learning that quick sequence is faster than using a mouse, if you want to make lots of new folders one after the other (it will react as fast as you can type it).

Windows xP still has a program called Notepad, very basic* , but does all you want to store information. (Win 7, 8 & later may have dispensed with it). Find it from 'Start' [button], 'All Programs', 'Accessories'. The files created will almost certainly be saved in your My Documents folder, from where you can drag them (in bulk, if you know how to do that) to the New Folder you've just renamed.
*e.g. you can't format the text: I'd use CAPS to distinguish the title, and use the Tab-key to separate different groups of information, such as Artist, Title, Record Label, Date [when you find it], Condition, etc. in the same order, one per line. It doesn't matter if the text spills over into the next line, or shifts what you've typed left-wards off the screen [click' Edit', 'Word Wrap' to cure that], that's still all one "line"., to the computer; until you press Enter to create a new line.

Hope you haven't got a Mac, 'cos this info will be of little use to a non-techie!!

As Dave the Gnome suggests, it would be more useful to enter this in a spreadsheet but, if you're a technophobe, the basic word-processor is less frightening. Hope this helps.