well, I suppose then moving onto other parts, it seems you still need a motherboard, a powersupply, memory, potentially a graphics card (this is usually only if your cpu has no integrated graphics, though a discreet gpu can also be useful, like for passthrough to a virtual machine, or other tasks. If you have integrated graphics and dont know you want a gpu, you're probably safe), disc(s) and a case.
if you're interested you might want to look for a coreboot/libreboot friendly mobo.
you should be able to get optic drives, without much difficulty. I am sure some people make them new, as they are not totally unused, but there's no harm saving a little money and buying nice used items.
as far as discs, you'll probably have to pick between SSD, HDD, or them both together. SSDs are nice because they are considerably faster than HDDs, but tend to be more costly and more prone to failure.
there is more to say, but I am not fully sure how much background you have/how much detail I should give, a lot of this is fairly easy to research on the wired yourself, but from when I started I know it can be fairly nerve wracking to actually make the jump to assembling a pc, and now its easy to forget how worried I was about wasting a bunch of money on memory that didnt work.