(I guess you would like to have a covering letter to your resume. A covering letter should not generally take much of the employer's time. It should state in a nutshell about your qualifications and your eligibility and experience, if any, to meet their expectations and requirements.)
With reference to your advertisement (quote the source where you got the news), I would like to apply for the post of Management Trainee in your reputed ABC Bank Limited. As I am almost about to complete my MBA in December this year, I hope I can meet your expectations and requirements. I have here attached my resume for your kind perusal, which, I hope, would give you a vivid details about my educations, experience and my accomplishments in general.
Thank for your time and looking forward to hearing from you soon.