Hello Kethavath,

SBI recruits Probationary Officers who start their career as Assistant Managers and then move on to higher Management. SBI Chairman, Arundhati Bhattacharya also entered as a PO. You need to give SBI PO entrance exam which is basically an aptitude test. Once you clear the aptitude test, you need to appear for Interview. After 2-3 years of experience, you can be given the responsibility of the Branch Manager. 

Keep referring SBIs career section for the next notification. SBI is on a recruitment spree and targets to recruit 1000+ PO each year until 2020.

Public Sector Banks follow the same procedure but the exam is different I.e. IBPS CWE for PO/MT. Refer to ibps.in for further details.

To appear for these exams, you need to prepare the following topics -

• Quantitative Aptitude
• English Comprehension
• Reasoning
• General Awareness with focus on Banking
• Computer Basics

Follow some bank PO preparation websites for details on how to prepare for the above topics. Just google SBI PO or IBPS PO and you will find numerous sites that specialize in it. 

All the best.