You can find your FTP details by logging in your Customer's area and clicking on the My Account tab. Under my accounts you will a "Manage" button for each of the hosting accounts you own.
Clicking "Manage" will provide you with your FTP login which is the same as your cPanel login. You can reset your password from there as well.
We also recommend that you check our FTP tutorial for more information.
SiteGround provides the best FTP hosting and we will help you with any FTP questions/problems you may have.