I just purchased an old Samsung stereo system. It is from 2008, the HT-z410t. https://www.cnet.com/products/samsung-ht-z410/
It only came with three connectors but I’d like to attach more speakers but I can’t figure out a makeshift way to attach the basic stereo wire I have. Is there a place I can order more of this cable or does anyone have any suggestions?? https://ibb.co/vv5FFt5
Interesting! It's got some decent spec's (except S/N ratio). About those connectors, I'm sorry...no clue. They almost look like the profile of the AC cord connectors which plug into DVD players. If so, there are your connectors. But the amp's loaded at 3 ohms, so if you want to add speakers, they'll need to be wired in series for 6 ohms. I doubt that amp wold survive added speakers in parallel at less than 3 ohms. Of course, you could run the outputs into an impedance matching speaker selector. That may keep the impedance from dropping too low and cooking your amp...that is, if you can find those connectors.
Most HTS systems us proprietary connectors so you can't usually get them except from the manufacturer and sometimes not even from them.
You can see the two pins for each speaker. You need to connect your speaker wire to those.
If you can measure the diameter of the pin you may be able to find individual female plugs that can accept the pin and not be too large for the jack.
If you have good soldering skills you can solder wire/terminals to the pins. Too much heat will damage the amp so you have to be careful. Any tech should be able to do it without charging too much.
I assume you just want to run center and rear surround speakers rather than use more speakers in parallel on the same channels you already have speaker connected.