You can add sheets easily by pressing ctrl and dragging the tab for the
sheet at the bottom. That makes a copy. You can also right-click a tab and
choose insert to create a blank sheet. Shift-F11 will insert a blank
worksheet.
Usually Excel opens with 3 worksheets, but you can change that in
Tools>Options, General Tab and at "Sheets in new workbook:" click the spin
button or type in the number of worksheets you would like Excel to open with
by default. I have seen people change this to 30 sheets and only use one,
then send the bloated file with 29 blank sheets, so use good judgement on
this.
