Firstly, your PIC16F887 is a 14-bit core device and the ASM manual is here MPASM™ Assembler, MPLINK™ Object
Linker MPLIB™ Object Librarian User’s Guide

Next thing you really need to download is the data sheet PIC16F887

Also, download this FREE book and read it to understand how a PIC works PIC Microcontrollers

The last one is the most useful - I pointed this out to you in an earlier post.