How can i add background music in a record?

i want to make a app, which is background music adder… that is add a music on a record. so, how can i do this ??

any one help me…please…

please explain in more detail

can i add background music on my recorded sound??

… and again, please explain more exactly:
should the music play simultaneously with the recorded sound or should the music be recorded together with the sound?

i want to make a system…which is internally add a background music with my recorded sound… can i do this?? have any way??

use 2 players and play them at the same time

but, i want internally. if i play music on player…that time sound play in loudly. i want to internally means mutely adjust record & music …

So I asked twice to explain it more … and I still do not know what exactly is intended …

If you want to make the music quieter during sound recording, simply turn down the volume of the music if recording starts.

Dear, i want to add background music on a recorded sound.