You have to demonstrate to immigration officials that you have enough funds in your bank account to cover your course fees for one year or the whole length of course if shorter than a year and enough living expenses for your first 9 months stay in the UK which is calculated as £1265 per month for London and £1015 per month for everywhere else in the UK.
You should submit ONE of the following as evidence of funds:
A bank account statement
A building society/savings account type passbook
A dated and signed letter from a financial institution stating that you are the account holder, the account number, and the funds in the account held over the minimum 28 day period
You may use your parents bank account but will need to provide a birth certificate and accompanying letter from your parents confirming they agree for you to use their bank account