How can i get my high school diploma?

Ok,long story short,i've been really thinking of my future and i'm taking initiative now to make something of myself..I screwed up when i was younger,i didn't graduate high school,i want to enlist into the armed forces...what do i have to do to get my high school diploma? i don't want a GED,but it's an option for whatever reason i can't earn my diploma...where should i get information? I'm pretty intelligent in many areas minus math..that's one subject i failed every year,but I'm a lot more attentive and motivated now being 22 and have no doubt if it can be taught all over again i'll learn it wit ease...i don't know if i need a special cl for that or something..i just want to get my life together and would love info on where and how to get started...i didn't finish my 12th grade..so i need that entire year...and i failed a total of 9 cles grades 9-11...math being 6 of them....any help would be appreciated greatly.