At 11 yrs old, why would you need such an advanced phone? Anyway, so good jobs for someone your age would be babysitting, mowing lawns, walking dogs, weeding the garden, small chores around the house, washing cars. Start asking your neighbors if they have any small tasks that you can do for a few bucks. Sometimes elderly neighbors need help taking out the trash or carrying in their groceries from the car. You should also talk with your parents about this. They will probably have some ideas for you as well.
I applaud you in wanting to earn the money yourself. Good for you.