What items should be included in a balance sheet?

The sections you would find are assets, liabilities, and equity.

More specifically:

Fixed Assets (non-current assets)

Current Assets

Current Liabilities

Long Term Liabilities (non-current Liabilities)

Equity.

International accounting concepts do not give a defined layout for a balance sheet. So you can lay it out as Assets less Liabilities balanced to the Equity or Assets balanced to Equity plus Liabilities.