excel tutorial

drop-down list
http://office.microsoft.com/en-001/excel-help/create-a-drop-down-list-HA102809802.aspx
share workbook
http://www.excel-easy.com/examples/share-workbooks.html
protection
review->allow users to edit ranges -> protect sheet -> protect workbook -> share workbook
vlookup
VLOOKUP("cdsvf",A2:C10,3)        vlookup("search",range,cell content x # to the right of the found)
networkdays
=NETWORKDAYS(A4,B4)     networkday(start date(dd/mm/yy),end date, holiday)  exempt holiday weekend
concatenate
=A7&B7&C7    x&y&z = xyz
rank
=RANK(A11,$A$11:$A$15)   rank(selected value, fixed range)
filter
advanced filter->copy to another location->unique->filter out replica
subtotal
sort(expand section)->at each change in sorted column->use function->add subtotal to column displays subtotal