i ant to study some replays . but i dont know where to get them or buy
The wonders of Youtube.
Alternatively, if you prefer live action, you can consider Twitch (though you get a lot of downtime, ads and talking in between matches:
Spawningtool has some build orders. Otherwise, YouTube, GSL matches, or a series like Vibe bronze to GM is pretty good
_https://lotv.spawningtool.com/build/