Hello David, 

Thanks for choosing Mockplus. 

In Mockplus RP,  you can drag and drop the Panel component onto the artboard to create a scrolling area: 

Double click the component to enter its editing mode and put all your desired content there.

Then, all the content will scroll up and down as you wish. 

If you do need any content to float or fix on the scrolling area, directly exit the editing mode and put the content on any desired position. 

Hope this can help you.

Snow