Choose a mixing software package for your needs, not by what's cheap or how many tracks you can add and adjust. If you are recording yourself, for example, but intend to add several more tracks to each piece, go with an eight-track mixer, not a 64-track mixer.
Follow these steps to see how GarageBand from Apple uses the keyboard and mouse to mix music, both live (self-generated) and loops. Loops are prerecorded guitars, keyboards, drums and so forth that you can mix with each other or with music you perform and record. You can change the length of the loops by stretching them in the interface window, and you can try many different combinations.
Adjust the sounds with the sliders provided. They are preset, but you can change them with the mouse. Change the sound level with the keyboard using the "Sound" keys with the speaker icons.
Listen to the track several times, and check if the created new sounds are smooth and within rhythm. If not, start over until it fits. If you don't want to start over, experiment with the tempo and other parts of the creative process that are included within the studio programs.
Play music with the keyboard directly into the program. You can play straight piano or use the computer keys to play the notes in other, sampled sounds such as guitar, drums and oboe. An image of a traditional grand piano keyboard can be used with the mouse, or you can change it to show the corresponding computer keys for the notes.
Bring in entire pieces of music you've recorded previously to mix with loops or other recorded bits. You can do it directly in GarageBand by dragging the digitized piece of music to the GarageBand interface, where it will form a new track. You can add loops to the mix or record new material over the old without destroying the original.