The yellow is the ground wire, secure it to the block with one of the screws holding the engine to the engine mount. The infamous blue wire is used to ignite the glowplug, so stick it on the glow plug. The blue wire is not necessary if you have a glow plug ignitor, and typically not reccomended as it drains the starter battery juice.
I apologize for the questions, but your questions were very vague at best and I have not heard of anyone putting an EZ on a xxx-nt or the Mach .15, so I was trying to figure out what to tell you. I tried today to get a link for the exploded diagrams at Traxxas......did you try?.....but it kept locking up.
Friendly Advice; Being a Richard will not get you much help.
Mr T