Don't know how to install a 2.5 ssd

You don't have to go it alone, you know. A DS computer comes with Lifetime tech support which extends to helping you install upgrades, if you want.

There are two first steps you can take. One, your board will take a single M.2 form factor NVMe SSD. 5 times faster than a SATA SSD, it plugs into a slot on the front of your motherboard, and requires no cabling at all. You could look into those and see if you would want one. Should be pretty obvious where that slot is, or just look at your mobo info.

Two, some motherboards come with an indent or two, or some other convenient way to mount a 2.5" SSD right to the back of the board. Take the back off your case and take a look. While you are back there, look around for some free plugs just like the ones that already attach to your drives. You will need a free power plug and a SATA cable. The power plug should be bundled up with the cabling you will find behind the mobo. You may have to snip a cable tie or two to free one. IDK if you will find an extra free SATA cable or not. if not, look in the parts box they sent, and if you don't have an extra, you will have to buy one. It will plug into the front of the motherboard next to the two that are already there from the drives you have, and then into the drive you bought.

You can just take a look back there, but if you want to touch and move some things around inside your case, it's a good idea to unplug it from the wall and then press the power-on button for about 5 seconds to discharge the capacitors. Touch metal on the case to ground yourself, and then you're good.

When he says not all M.2s are NVMe, he means the pocket-comb sized drives, not the slots themselves. If you put an NVMe SSD in there, it will run off the PCIe bus automatically.

hose, the Lynx boards have only one M.2 slot, but that's interesting and good to know. By how much?