You can find the pinning information for the LPC55S06 on this MCU’s datasheet. Here’s the link:
For the connectors, jumpers, LEDs and buttons of the Development Board it comes with, look into the Dev board user manual:
Finally, the MCUXpresso IDE comes integrated with Config Tools, which allows you to set up and adjust the pin multiplexing of your MCU. With this tool, you can also check which pins routed to your board and how. The following link does NOT use the same board, but can still give you a good insight on how to install SDKs, import an example, and create pin muxing and clock configurations:
I hope this helps!