I have to be at which level in order to ascend? Can anybody please answer...

Ascension opening is same as starting an another story quest. So :
• You have to be lvl 60, (minimum)
• You have to finished whole main quest before Median. (Calpheon side must be cleared)
• You don't have to have another story quest under progress. So, better finish cron story line before 60 too.
After all of these when you reach 60, you get a warning about it or check under story tab to start ascension quest line.
Good luck

Awakening is not available yet.