You got soo much work to do...
lil'kiwi... try harder, hopefully something better will come out (like your rapping

)
Letter Structure - Yours is quite awkard to look it and inconsistent. I cant even tell what the first letter is. Try working on it so your length and style is consistent
Coloring - The colors are not only messy, they dont match. Try restricting yourself to 3 colors for now and not using marker next time, especially water-based marker.
Connections - As with many newbs, there are none. In fact, where your letters overlap it reverts to its background colour, making it look awful. Try simply overlaping the letters completly
Effects - The force field (2nd background) looks complely awful and doesnt even make sense. Try making it surround your blue background instead of just filling in random, created, gaps. Your 3d is on target, but missing in some places and too long in others.
Im sorry, but your graffiti needs a whole new life... that was completly awful. Nearly reminds me of my 9 yr old brother drawing to be critical. 1/10