You set AHCI mode of the SATA controller in the BIOS of your machine. You need to check and see if it's already in AHCI mode and, if it is, then you're good.
However, if the machine is not currently set to AHCI and you change it, the system will no longer boot from the currently installed OS. You will need to leave the SATA controller mode as is, boot the machine and make a change in the registry, then reboot the machine, enter the BIOS and then change the SATA controller mode.
Once you have the machine booting in AHCI mode, then you can proceed to migrate to the ssd as you have planned.
Here are the instructions for how to modify the registry: How to Switch from IDE to AHCI without repairing/reinstalling windows - A Collection of Essential Guides - Neowin Forums