Any good personal statement must address the following points:-
1. Why are you applying for the course (i.e. discuss how it will further your career ambitions, what do you find interesting about the course, how did you first become interested in the displicine etc etc).
2. Why you are a good candidate for the course (here you want to be discussing any relevant work experience you have done to date, perhaps mention how your A-Levels/BTEC qualifications have prepared you for HE study, your work ethic, any extracurricular activities, prizes won and so on).
I hope this helps and good luck. I would definitely recommend making use of your tutor/careers advisor too for further help and assistance.
You may also find some useful accounting/finance/business personal statements on the internet to inspire you (however, be careful not to copy or plagiarise).