pic16f84 led
Just to give an answer to this question for someone who reads this question:
Inversing the logic can be a solution, if the OUT port do not give enough current (mA) to drive the LED.
So, you can plug a resistor (maybe 500 ohms) in the +5V => then your LED => and you plug it into the OUT port. In your ASM program, instead of lighting it with a 1, light it with a 0 and turn it of with a 1. If you don't know, "0", in logic circuit, acts like a ground and 1 as a +5V opposition to another +5V if you plug it in the way I describe, which is common anode (meaning all plugged in the same +) instead of common cathode (all plugged in the same - ). To understand these two methods is very important when you're a beginner and want to design (ie: PIC16) circuits in Multisim and/or on a breadboard. Also, sometime this is easier and maybe funnier to design the real PIC16 circuit on a breadboard, since you take the time to make the good connections and an acurate ASM code.
If you still want to use common cathode method, Out-> Resistor -> Led -> Gnd, then you can choose in the led properties in Multisim how many current your LED need to light, but this is less real. And (i think) you're better not to take current in your circuit, anyway, it takes its current in the same source.