UART 1 activation

hi i’m really really new to linux in general and i don’t really get the u-boot kerne etc i managed to get my lichee working with linux in it and got xfce4 installed my problem is that i want to use UART1 and i don’t know how to activate i really have no clue any UART1 2 3 i know that UART0 debbugung is enabled and is working but for my application i need UART-1 please help
thans in advance