Definition is not "built". It is from other things being removed - fat, water, etc. You can be very defined wothout having any muscle mass by not eating or drinking much, but I don't recommend it.
Cardio work at moderate levels for a decent length of time can work to reduce fat and water and increase vascularity. But weightlifting works better and faster.
Don't bother with the supplements. Most of them are garbage. Just watch what you eat instead, and you'll be fine.
"In case you ever wondered what it's like to be knocked out, it's like waking up from a nightmare only to discover it wasn't a dream." -Forrest Griffin