For a complete list of everything that you should be publishing, see the Local Government Transparency Code
For expenditure its basically every payment over £500 to be published on a quarterly basis as a minimum (though you are encourage to go a step further than the minimum and publish it on a monthly basis and over £250).
You also need to publish procurement card data and details of any tender for contracts or contracts entered into that exceed £5,000.
See the link above for the precise details of what you need to be publishing.