Dual Boot Win 10 and Mint

Trying to set up a dual boot with Win 10 and Mint....
Older Lenovo PC.....I could not change BIOS to USB first boot.....but I can F12 and boot menu comes up....
Here is what I did...

Win 10 fully up and running....8 Gb RAM and 2 TB hard drive....
I shrank the volume and made 2 partitions about 900 MB each....
First partition is C:\ and windows is running great....

Second partition intended for Mint is not formatted....

Booted up with Mint on a bootable flash drive....
During install it did ask for a partition....I chose what I thought was the obvious one....
Mint appeared to install....I rebooted and expected the BIOS to ask which OS to boot up to....
But it did not....

Every reboot it goes into Windows....

And looking at my C:\ drive it does not appear to have anything on the "other" partition nor is there any linux files in the C:\ partition...

Disk Management shows a healthy C:\ partition and the other partition as healthy but not formatted....

Should I format the partition.....if so exFAT...????

Thanks for any assistence appreciated...