Begin by getting together a group of friends with whom you will be attending the concert. These will obviously be friends who are also fans of this particular band, and it would be best if these happen to be friends whom your parents are familiar with, and actually like. Make sure you are also on good terms with the parents of these friends, so there is no cause for worry or suspicion on either side.
Find out the cost of the ticket well in advance, and start saving money. If you already have enough money to buy the ticket by the time the concert rolls around, it is highly unlikely that your parents will spoil your plans by refusing to pay for your ticket. Gather your own funds and you will improve your chances of obtaining permission by a significant margin.
Chalk out a specific schedule for the day of the concert, so you do not leave your parents wondering on any account. This way, you will be able to let them know the exact timings for the concert, who you will be going with, and how you plan to get to the venue and then back home. Already having a plan in place will act as a major convincing factor.
Now, once you have planned it all out, choose the best time to broach the subject with your parents. Do not talk to them when they are stressed out, or in a bad mood. Choose a time when they are calm – e.g. maybe when they are settling down to relax after dinner.
Speaking in a calm and casual tone, inform them, maturely and responsibly, of how you have saved up money for a ticket, and how you want to attend the concert with your friends. Give a reassuring answer to any questions they might have. If your parents do not agree, do not whine or complain. Drop the subject for then, and then try asking for permission again after a day or two has elapsed, and your parents have had time to think about it.