How to connect my new PSU and GPU?

I went to a store and bought a Seasonic Focus GX 750 Gold ATX 3.0 and an MSI 4070 vemtus 2x 12gb. Store guy said they'd work together, but I cant find a way to connect them. Psu has no dedicated gpu slot, only the 12VHPWR slot and a bunch of regular pci-e slots. Gpu has one 8-pin connector.

How do I hook it up? Can I just ignore the 12VHPWR slot and put it in a regular PCI-E or do they not have enough power? Gpu is rated at 200W.

Send halp pls