How to install macOS? What to do with disk partitions?

Question

macOS

Hello. I apologize in advance. I've never used a Mac before, only windows. There are no problems with the latter, I can do everything with my eyes closed. I bought a poppy and it hung ...
In general, the initial data is a macbook 13 "2015. When I bought it, it was catalina. I read somewhere that it would be better for this poppy if you put Mojave.
The key combination, when rebooting the system, went into the disk utility. Deleted data from the SSD drive (cleared it for further OS installation). I thought that there would be an opportunity to choose the OS for installation. But he offered to restore the OS via the Internet. This is where it stopped. El capitan was installed all night (a nightmare for how long). Now it costs accordingly. I'm also a noob when it comes to disk partitions on a Mac. On Windows, he could partition disks when needed. But lately, I just stupidly put the system and all programs on SSD 128, and the rest of the content on 500GB. Here in the disk utility I have my SSD displayed and there is a subsection. I don't understand why? That SSD that its subsection can be deleted. At what volume they show the same. That is, this is not my main SSD divided into 2 disks. Because then they would have different volumes.

I opened many sites where it is shown how to make a bootable USB flash drive. But one fig does not work.
I downloaded the mojave installer from the app store, through the terminal I wrote what was indicated on the site. Doesn't want to load.
I also did not understand how to open the boot selection window when the system boots. On the Internet it is written that when loading, you need to hold down the Option button. I tried but I have disk utility loaded. There is no choice from which drive to load the OS.

I also don’t understand when I open the Finder, I see there - a flash drive, a usb flash drive and a "remote disk". I remember that before the reinstallation there was something like mac xd. Where did it go and why this remote disk I do not understand.

When I try to make a bootable flash drive, I get to the point where I formatted and renamed the flash drive, I enter the command in the terminal, and in response to me -
to use this tool you must download the macos installer application on a mac with 10.12.5 or later

Answer 1

The easiest way to make a bootable USB flash drive is with the DiskMaker X application.
During installation, boot from it and completely erase the laptop's SSD drive using Disk Utility, without partitioning.

Answer 2

to use this tool you must download the macos installer application on a mac with 10.12.5 or later

Well, with this, I hope everything is clear? your system is too outdated, it is written in black and white) The
poppy is quietly installed via the Internet, as you did 1 time. The installation speed depends solely on your Internet. he has to download the entire image to install. there is about 5-8GB ...
Go back to recovery, delete all disk partitions, and let it set as you did the first time. Therefore, it is easy to update with regular means, through auto-update. That's all ... why suffer then

Answer 3

Yes, sir. Seems to have figured it out. Understood at the expense of the inscription.
I just downloaded the mojave installer from the Apstor site and launched it. The captain has been updated to mojave.
The remote disk was simply removed from the finder, now it is not displayed.
At the expense of 5-8GB. I have 500 megabit internet. I think it’s clearly not 8 hours to download at such a speed) We see there was something on the Apple website.
Thanks guys, sorry for the stupid newbie questions. Makos is not known to me at all, I will learn slowly.