It is basically quite simple to reference from one sheet to another.
Start off with just one cell in a new sheet. Insert an = sign into it and then (without doing anything else) just move to the sheet you want the reference from and just place the cusor into the relevant cell so that it becomes highlighted; then click the tick beside the entry box at the top; this should then take you back to the original cell and display the value from the second sheet inside the cell; at the same time the formula in the box at the top would show something like: =Sheet1!A1
You could of course just enter the formula in the box but moving the cursor around is much easier.
You can then drag that cell all over the place to reference multiple cells on the other sheet.
If you ever want to reference just one cell (something like a percentage rate) which is kept in just one cell somewhere you can use the $ sign so that when you drag a cell around it continues to only reference one cell somewhere. Thus if you altered the value above to =Sheet1!$A$1 then the A1 cell in Sheet1 would continue to be represented wherever you drag the cells to.
Hope I haven't made this too complicated because its dead easy once you get to grips with it.