I'm buying a PC from my buddy, it's my first PC, and I was hoping for some advice on pretty much any and everything, seriously ELI5 I want to eventually replace everything in the PC but I just learned that Upgrading is different from replacing so I realized I know NOTHING about anything lmao. Here's what he sent me when I asked for specs

4690k and MSI GTX 950. It's an AsRock Z97 Extreme 4 Mobo with Corsair Vengeance DDR3 2400mhz. It's a Samsung 860 Evo SSD (250gb) and a WD Blue 500gb. That's should be all the correct info for ya. And a Swiftech H220 X AIO cooler with an additional 4 case fans. And a NZXT H500 Case with a Corsair CX750m PSU