Why is xubuntu 17.04 not showing up after installation?

Question

ASUS

Original:
Asus K50IN
One disk is divided into 3 partitions in Windows 10
Windows 10 and Windows Server 2016 are already installed on the laptop.
Nevertheless, I decided to slowly switch to Linux, at least at home, and start studying it for system administration in full. I installed the system itself more than once and more or less use it as a workplace at work ubuntu 14.04. I came across for installation and Centos7 on which I'm torturing zabbix now. I have never put a Linux system right next to Windows. Often I have either Linux or Windows where the virtual machine is Linux.
Created a bootable flash using Win32DiskImager. I put Xubuntu on a free partition of 100 GB, everything went well, rebooted, and in the selection list, Windows 10, Windows Server 2016 are still only available for download. What am I doing wrong? I assume that you need to pick something in GRUB? As I understand it, I will again have to boot into the Xubuntu installation and select "Try Xubuntu" and what next or am I picking in the wrong place?
By the way, how to split correctly during installation, because I usually let everything be done automatically, but in my case, two systems on one computer? I made a partition "/" and stupidly continued to put everything on it. Everyone is perverted with separate /home, /tmp, /swap during installation, which is not clear to me to some extent, for what?