Connect a MIDI keyboard, if you have one, to your computer. Insert the USB connector into any available USB port on your computer. Connect a MIDI USB adapter to your computer's USB port if you have a standard MIDI keyboard. Insert a MIDI cable into the "MIDI Out" jack on your keyboard and into the "MIDI In" jack on your computer adapter.
Click on the Reason icon on your computer to launch the program. Click the "Create" menu at the top of your screen. A drop-down menu appears that lists your available software instruments. Click on and select any instrument on the list. The virtual instrument appears in a separate window, along with a list of effects, parameters and preset sounds. Adjust the preset parameters to tweak the sound to your desired specifications, or select a factory setting from the on-screen menu.
Click on your MIDI track on the main software window. Click the "Record" button to record a MIDI sequence. The MIDI track looks like a horizontal bar on which you record a MIDI sequence. The bar stretches across your project window.
Play the keys on your MIDI keyboard to sequence notes to Reason. Sequence notes individually with Reason's "Edit Mode" if you do not have a MIDI keyboard. Click the "Edit Mode" button near the upper-left corner of your project window. A grid appears when you enter "Edit Mode." Click the dots on the grid to enter notes. The higher dots correspond to higher notes, and the lower dots correspond to lower notes.
Create additional MIDI tracks by selecting new instruments beneath the "Create" menu. Each instrument creates a new layer of music, on which you place additional instrumentation. For instance, you might record an electronic drum sequence on track one, and then add a synthesized bass line on track two.