u should learn more about playing the guitar, diffrent tunings for an guitar means you the tension on the strings are higher or lower, you need to have an guitar tuner to tune your guitar,
as much as you want you cant make giant steps. learn the basics of playing guitar than practice practice practice eventually you can play COB songs,
and to get the same sound as Alexi is almost impossible, the brand of the guitar doenst make you sound like the artist using them, its the playing techniques, the feel for music, the equipment like amps and pickups.
you can get the same Equipment as alexi had, but still than you wont sound like him. because you simpelly are a diffrent person !