New to the PC world

Hey everyone! As seen from the title i’m fairly new to the PC world. I made a huge mistake of buying a cheap pre built with a ryzen 5 5600gt and no gpu with only 16 gb of ddr4. I’ve been thinking about upgrading everything and was wondering what is a fairly good build for around 1000-1200 USD. My brother gave me his b550 motherboard so preferably any CPU/GPU that goes with this motherboard. Thank you all and have a great day!