Some peoples are using a cardboard to hold the hdd, because the Super Slim doesn't come with a hdd mounting bracket, which is logic since it doesn't come with a hdd. I don't recommend using a simple cardboard though, better to do things properly in my opinion.
That's what you are looking for:
Great. that means you get to put your HDD. I assume it doesn't have a HDD tray too. So you might want to buy it either on Amazon or ebay. Just search PS3 HDD tray. I bought this. But you can find it like $1 cheaper on ebay
Any version will work technically. The caveat is the stock superslim comes with a 12GB drive by default, which is not enough for system software, the game, and the cfbr installers. All other models come with at least 60GB I think.
If you want a superslim, you can just get this bracket that goes inside the PS3 and any $15 SSD off best buy or amazon and you should be good to go. Doesn't take much to install, just a screwdriver. Your system should also be a bit snappier with an SSD installed vs a 15-year-old hard drive
HDD tray for upgrading the HDD.
Pretty sure any 2.5" drive up to 7500rpm will work. Or a decently sized SSDD. That 12Gb won't even get you one digital game.
Yeah, sounds like you have the PS3 Super Slim, which comes with a wimpy 12 GB of storage space. Even though a game may be, say, 9 GB in size, several more GB may be needed once uncompressed and installed. Time to upgrade that hard drive, which isn't quite straightforward with some Super Slim models....If you find that your unit is missing the drive bay slider, you can order one cheap on Amazon here.
your missing the hdd tray for the harddrive, you can buy one here:
Sabrent makes a mounting bracket that works well. Then you just need a 2.5 inch HDD ( <= 1TB ) and a USB flash drive to put the firmware on.
https://www.amazon.com/dp/B00LS268YG?ref=ppx_pop_mob_ap_share