Hello Diane! Thank you for asking this question to first say thank you for the note earlier today. I intend to get back there later tonight to respond. The second answer is for sure many are lyricist and do not write music or another writes the music. Look at a well written Beetle article and that light turns on. From the little I have looked into with just casual reading many song writers of the 60's - 80's were that first and then later became soloist. A pattern is they wrote lyrics or songs with lyrics for those all ready in the mainstream entertainment industry.
I wrote a lyrical poem and friend at work placed it to a simple chord whatever it is called for guitar. Works for me, even though I do not play a guitar. A question I would like to ask may sound odd. If you have the lyrics do you hear the music already? I have a friend in the UK who see colors with music. Both a nuisance and a marvel. As music is played the imagery in the mind changes colors with the music. It is called synesthesia. I think it goes both ways see colors and hear colors. Not sure.
If you live near a college campus I bet a bottom dollar a bulletin board and an agreement either bartering or such and such could be had for an opportunity. Do have a great day . . .