so on the summary sheet you simply type in an equals sign and then point to the cell in the first sheet (you'll see it say "sheet 1:B22" for instance). Now you can change B22 as much as you want and that will be reflected in the summary sheet.
"Paste Special" is used when you want to take something that's been calculated and save just the value that's currently in it. (for instance, if you go to D2 and enter B2+C2 in the formula bar, you'll see the sum in D2 but in the formula bar you'll still see the FORMULA. If you COPY that cell, then paste it somewhere else, just plain paste, the formula will be pasted in and will change if you change the contents of B2 or C2, wherever you paste it, in the same sheet or a diffeerent sheet. IF, on the other hand, you Paste Value, then the *actual sum* of B2 and C2 at the time you did that calculation will stay the same when it's pasted in elsewhere. Play with it and you'll see how it works. It's a very useful trick to learn.