A hearty welcome.
A really fine and relatively concise overview history of western music is in the Penguin editions,
History of Western Music, volume two. [Volume one starts in very early history; Volume two starts with the early medieval, runs through to the twentieth century -- that last part very likely expanded and edited since I read it decades ago.]
It traces the development of classical music, harmonic development and shifts of forms, while keeping very much in the limits of the layman, with perhaps your wanting to look up a few terms for further details.
It cites important composers of each era as well as some works which are near to the "embodiment" typifying the essence of the era, and some milestone pieces from various composers that mark some notable influence or trend of a stylistic shift.
When it comes to the names of those eras -- those were named [somewhat arbitrarily] in the mid to late 19th century; the 'modern' era is from ca. 1890 to 1975, and the dully named post-modern era is literal, having nothing to do with 'post-modernism,' but meaning only, 'after modern.' So far, composers have not conveniently shifted the style in which they wrote, nor died conveniently, on or around those set dates for the different eras: those dates are general guidelines, that is all.
The Wikipedia article on Classical Music is extensive, and also more than useful for your intent. It has sub-chapters on each era, composers for each era listed chronologically, and many of those names are active links which will bring you to more about that composer and some of their more essential works.
After that, my friend, Youtube is truly your friend; you can find a lot of classical there from the earliest repertoire to the most recent, audition it, find what interests you and then pursue further as to your plan or whims. When it comes to more specific recommendations, bring them back to the forum. That would include specific recommended recordings as well. Collectively, the members of a forum like this one are one huge resource library.
I've found that those who listen to metal, prog-rock, haus, etc. i.e. music which is solely 'a bunch of notes which make a collective kind of sense [Jazz is included in this same arena] are usually well oiled and primed for easy entry into the classical repertoire, because that is exactly how one listens to classical.
You've been listening to a lead guitar, rhythm and bass guitars, an equivalent of chamber music -- a handful of musicians all directly involved in the fabric of the piece. I invite you to not forget to explore the chamber music, the trios, quartets, quintets and sextets of all strings, all winds, or mixed instruments, sometimes including piano. The musical activity is usually much clearer and 'easier' to follow. Chamber music is a more direct and intimate experience with the individual instruments and instrumental families that also sets you up well for listening to music with full orchestral ensembles.
I envy you in it all being new to your ears, and the experience of exploring, each piece being a discovery.
Have a blast, come back to the forum, please, not just with further questions but also let us in on some of your reactions to the music you've plunged into....
Best regards
P.s. Just for the helluva, try these:
Dmitri Shostakovich - Two pieces for string octet, op. 11 - N. 2 Scherzo
https://www.youtube.com/watch?v=ukvKZqBN808Bohuslav Martinů:
Toccata e Due Canzoni (1946) I. Toccata
https://www.youtube.com/watch?v=WMZw0uoRc4wDouble concerto for two string orchestras, piano and tympani
https://www.youtube.com/watch?v=Gh9fkbMfSJAArthur Honegger ~ Symphony No. 5
https://www.youtube.com/watch?v=ibtoWic9GQ8https://www.youtube.com/watch?v=UfVP8f7iIMUhttps://www.youtube.com/watch?v=XlJNcfxXRy8
