To test the state of a bit in a register use the BTFSS or BTFSC instructions.
See the Instruction Set Summary towards the end of the Datasheet for the chip your are using.
To change one or more bits of a register use the BSF or BCF instructions
Code:
movlw b'00001010'
movwf d1
btfss d1,1
goto iszero
notzero bcf d1,1
result is b'00001000'
I hope ive got that right, if so, I understand
I knew BSF could be used on the port and tris registers but I wasnt sure if they could also be used on user defined registers.
Yes you have the idea, thats the easy way, though there are other ways of doing the same thing.
Do you use Mplabs Sim ? - its very helpful for single stepping through your code one instruction at a time and viewing W and the registers values changing in the Watch windows