Auto-populate data to a master worksheet from other sheets in a shared workbook

I have never really used VBA and so am completely stuck at this problem. I need to create a macro which auto-populates a master worksheet from the individual user sheets in a shared workbook.

Sheet 1 is the master sheet "Team Stats". There will be an undetermined number of individual worksheets to accomodate new staff.

Each worksheet will be identical, using columns A-I with row 1 having the headings:

Date, Name, Reference, Value, Price, Age, Purchased?, Destination, Add. Products (the last 3 columns will have a drop-down list which will be used to enter data into the cell).

There will be a varying number of rows in each of the individual sheets.

If possible I would like the macro to run every time data is entered into one of the individual worksheets. If this is not then it would be fien to update every time the workbook is opened.

If anyone can help it would really cut down the time I spend collating these stats every day!