how to interface RS-422 to UART on my MCU?
There are plenty of standard RS422-to-LVTTL conversion ICs available, so this should be straightforward.

Have a look at the following devices. Their data sheets should guide you on how to connect them to you UART's serial data output (TXD) and serial data input (RXD):

Maxim MAX3086

Texas Instruments family SN65HVD30 to SN65HVD35
Search TI website for data sheet 'SLLS665K'