@MSigol
You haven't said what unit you have, but this is universal: In sd root, create a folder named Garmin. Inside copy the unlocked Bluechart named as gmapsupp.img i.e. x:\Garmin\gmapsupp.img is the path. Also see catymag's post above yours.
Don't bother to try to use MapSource when working with Bluecharts. It can be done but it's a pain in the butt and near useless anyway. HomePort is the correct program for Bluecharts. It will see them on an sd card regardless of their name (i.e. you can chose any name: AnyConvienientName.img), in a folder named Map as well as the Garmin folder. It will even see the images if still locked.