No problem, if you don’t bet much it isn’t necessarily that intuitive. For instance, every bet technically ends up a money line bet. In the previous example, if you bet Iowa + 4 (Iowa will lose by less than 4) or ISU -4 (ISU will win by more than 4), you still have anywhere from a -110 to -120 moneyline. The $10-20 is the cut that the casino/sportsbook takes. So even with the point spread, you have to bet $110-120 to win $100.
Never done any sports betting. And that’s why. Don’t know enough about it! Understanding it more now.