It is not possible to answer your question without more detail. What is your monitor? Does it have an AV input? Does your Sony have an AV output? (probably)
I use a NextBase 9" DVD player, it has an AV input which I connect to the AV output on my camera (normally a Yellow BNC plug) It works OK. Whatever the monitor you choose, it will need a composite video input and you will need a combimation of cables to connect to your Sony.
I suggest you take your camera to the monitor supplier and see if you can get it to work.
do a lot if table top instruction videos and the problem is i have to keep flipping the LCD screen on the camera from front facing the lens and back. Doing this in time breaks the fine connection to the LCD screen. I thought a way to solve this was to set up a remote 7 inch monitor on the table. Question is can i use one of the 7 inch monitors for a car backup camera or the monitors for the headrest used in cars? i can buy these for around $35.00 but i don't want to buy one and find out i can not plug my Sony handycam DCR SX40 into it or it will not work while making a video