How to install a boot menu after Netrunner install

Hi.

I installed Netrunner alongside Windows 8.1, but now my pc boots directly into Netrunner.

How can i install a boot menu so that i can select Windows or Netrunner during startup?

Kind regards from a newbie.

This is installed by default normally. What happens if you hold shift right after bios or efi. Can you enter the boot menu there and choose the os to boot?