The datasheet gives you all you need, there's a page which gives a bit representation of the config word - simply select which bits need to be high, and which need to be low, from the descriptions provided.
A good practice in programming is to avoid using "magic numbers" as constants. That is, avoid using statements like "__config 0x3D18" because you will have to go back to the datasheet to decode what the values mean. In addition, you will have problems transporting you code across different devices.
Here is a sample of the code I would recommend:
Code:
LIST P = PIC16F818
INCLUDE "P16F818.INC"
;
__CONFIG _MCLR_OFF & _LVP_OFF & _INTRC_IO
END
To configure for 32Khz operation you would also have to initialize the OSCCON register.
The include files are supplied by Microchip if you install their MPLAB IDE development system. There's one for every device type they have. They can be found in the "\Program Files\MPLAB IDE\MCHIP_Tools" directory.