You can do this by using different voices. To use different voices, input your higher notes as you normally would. Then go down to the bottom of the screen. Now this differs a little depending on if you are in finwin or fin/Mac, but you should be able to choose voice 2 by clicking a button or using a pull down menu. What voice 2 will do for you is allow you to enter a whole new measure of notes on top of your already existing measure of notes (say putting your quarter notes under your eighth notes). Finale will automatically put the stems up in voice one, and put the stems down in voice two. I believe the default will also display voice two in a different color so that you can tell them apart. (I think the color is red).You can do lots of things with the different voices and lots of finagling to make it look good, like changing stem directions and hiding extra rest, but I didn’t know if you wanted to get that complicated. If you want to know more, just e-mail me and I can go much more in depth if you would like.
Hope this answers your question.
Shane