I have Kenwood Receiver form 1975How do I hook up a CD player ?

Into the aux jacks or tape monitor output jacks. Check Amazon, Audiogon or Ebay. They are everywhere,have fun.   

Garebear,

You can connect a CD player to any line level input, such as tuner, aux, etc. Do not connect it to the phono input. You would connect it using an Interconnect cable that has a L (White or black) & R (Red) RCA jack on each end.

Single disk CD players are still readily available for manufacturers such as Denon, Yamaha, Cambridge Audio, etc. You can also use any DVD player to play CDs.

I agree reubent,
search Craigslist, eBay and Yard Sales for cd players- they are everywhere.
Happy Listening!

"how do I hook up a CD player to that receiver? Also, where would I buy a single disc CD player these days ?" 

you have been a member since 2000 on this site and have over 414 positive feedback....and you are asking this kind of question ?  

just seems a bit odd......