[SOLVED] Installing to Dual-Boot with Windows

[me269]

Back up the current working W10 installation using something like clonezilla prior to starting as insurance.

I haven't done a dual boot install for a while, but I believe all three methods you've researched are viable.
The simplest is option 1 (install alongside Windows 10). Ensure the installer is directed to use the free space you've made.

Thank you very much for your response. How do I ensure that the installer is directed to use the free space? 

If I choose "Install Linux alongside Windows Boot Manager" (option 1), I get the following message:
"The following partitions are going to be formatted: partition #6 of SCSI1 (0,0,0) (sda) as ext4"

How do I know that partition #6 is the free space? Is it automatically selected because there are already 5 existing partitions?

Or would it be safer to choose the "Something else" option and use option 2 or 3? If so which of option 2 or 3 is more likely to be successful?

Thank you