The Process is same as Installing But, You need to Back your files up for this.
Follow this Guide for Installation and Re-installation,
A simple way to tell if your OS is installed on SSD or not is to run a command from a terminal window called lsblk -o name,rota . Look at the ROTA column of the output and there you will see numbers. A 0 means no rotation speed or SSD drive. A 1 would indicate a drive with platters that rotate, which means it's an HDD.