Seriously drop the idea of the 1tb mech drive , if you can afford it fine but its at the bottom of a list of more important things.
6 core 2600
16gb ram
radeon 570
500Gb ssd.
Motherboard
Thats your core.
You will need a case, cooling, psu (something decent not cheep and nasty), DVD drive if you want although i wouldnt, licensed copy of windows, keyboard, mouse, speakers (if needed) and of course the monitor.
Then after all that, if you have change then yeah go for a big hdd but i would spend it elsewhere first.
Then of course building it, and thats not easy - its easy to do it poorly as many do (hell the number of pc's come across my desk that look like its #myfirstpcbuild lol)