Ascendation is when you reach a certain amount of power. When at that stage of power you greatly increse your abilities and strength.
No, you do not get bright blonde hair and green eyes like in Dragonball Z.
Once asceded, you can get back to that stage any time you like.
You normally ascend while in a limit break, but not many people realise this.
There are 3 stages altogether. They can all be reached through anger and loss of family.
Look at the picture at the top of this page. Think of ascendation of this. You go up the power line, smoothly and when you get to a certain amount of power you come to a lift. The lift goes up and down, up and down. It never stops moving. You have to wait for the right time to get onto the lift, or you will fall down the shaft. Once gone up and out of the lift, you acheive a whole new load of power.
To ascend, all you need to do, is the limit break exercise while at a certain amount of power. This amount of power is not measurable, so you will have to judge for yourself. Train until you get to this amount of power.
While ascended, you will feel brilliant. A whole mass of energy flowing around your body. The feeling is undescribable. You will just 'know' when you are ascended. I am currently ascended to level 1, and my hair on my body grows way faster than normal. I cannot control when I ascend, so if I get really pee'd off I will ascend automatically. This can be highly dangerous, because you can really hurt someone while ascended, so I have to be careful not to get really angry.