I am new to Raspberry PI, but not new to building my own computers, so I have some ability. I got the iUNiKER Raspberry PI 4 B 8GB kit off of Amazon. I had to update the Noobs to the latest version. But then I found out that the default OS is 32-bit. I need to run a 64-Bit OS for the work I'm going to be doing on the PI. So, I've been reading some postings and they talk about imaging. But I remember reading somewhere before I got the kit that it is possible to have multiple OS's on the microSD card and then to choose which one to load, or something like that. I need more specifics. I can download the Raspian 64-Bit OS "image" file, but I'm at a loss of what to do with it to make it available on the 64GB microSD that came in the kit. Do I just make a file folder in the OS folder, and copy the image into there? or is the "img" file misleading me, and it is really just a set of files and folders that are in a file that is using .img as its extension? Is this really just a zipped folder name? I'd rather not buy a microSD card just to play around with. And I don't want to mess up the card that came with the kit. So, if someone with more experience can give me some better clues/directions than what I've found so far, that would be greatly appreciated.