Instrument Sounds

Hello. I just downloaded this program after using a paid one at school which I don't have myself. I don't have the money for the paid one, but on it, you can go to Mixer and change the sound of the instruments. On here, I went to mixer, but the only sound available is bright piano. Is there an add-on program or something like that that can allow me to hear the sounds of other instruments, such as oboes, English horns, clarinets, and other beautiful instruments? I appreciate any help I can get.