Sure you can
Get a cable with one 1/8" stereo plug on one end and two RCA plugs, one red and one white, on the other end.
Plug the 1/8" stereo plug into your sound card's output.
Plug the other two plugs (red=right channel, white=left channel) into an unused Aux input on your Sherwood.
Turn all the volume levels down LOW and then turn on the PC and the stereo.
On your PC, play a music file. Put your soundcard output volume at about maybe halfway.
Now select the Aux input on the receiver and SLOWLY turn up the volume. You should hear the music file you're playing on the PC.
Adjust the levels if necessary. Don't turn up the output from the PC too much or it may sound distorted.