program to add music to a recording

yea i had a question...
I recorded a song with The sound recorder that comes with windows...
now my question is....
if theres a program out there that has piano, drum beats or guitar beats recorded on it? like prerecorded beats or sounds on it
so that i can intigrate it into the song??
i hope you understand what i mean because i dont quite know how to explain it....
thanx for your help in advance