Welcome to the forum.
Can you please confirm whether you understand the CAN basics?
You need a bus with 120Ohm termination resistor on each of the two ends. If you have two modules with resistors make sure they are enabled. Many modules have jumpers for that. If you have more modules make sure only two resistors are enabled.
You always need two CAN modules. One module cannot send a message successfully into the void. You need at least two modules and they need to be set to the exact same CAN bit rate. A module with a different bit rate will create errors and stop after a while until the bus is quiet.
A single module will repeat a message continuously because the send will never be successful.
Do you have an oscilloscope to look at the signal on the bus? Any cheap, old analog oscilloscope will do for CAN.