trying to run an led off of 4 triple A batteries
If the batteries are in series it should be possible.
You'll need to calculate a current limit resistor in accordance with Ohm's law.
Formally for that, you need to know the forward voltage of the LED, and the rated current.  But if we neglect the forward voltage entirely things will just come out on the dim side, and if we guess for say 10 milliamps you are probably OK with most LEDS.
So applying ohms law, 4 * 1.5 = 6 volts divided by .010 amperes yields 600 ohms.
Resistors come in a series of well spaced values that superficially look funny but actually do a very good job of providing choices.  The closest choice in the most common series would be 680 ohms, but 470 ohms is also available in that series and would not be unreasonable as a starting point either.  You may also find 560.
So, put your 4 batteries cells in series, then from the positive lead of the most positive battery cell connect to your resistor, then from the other side of that to the long lead of your LED, and from the short lead of your LED back to the negative side of the most negative battery.
If you knew the forward voltage of the LED, you'd first subtract that from the battery voltage before calculating; if you had the current rating of the LED, you could start there instead - but &quot;junkbox&quot; parts exist, most people won't hesitate to reach for an indicator LED for a one-off project just because they don't have its specifics.
Speaking more generally, you could also use three cells with a smaller resistor.  If the LED is a red one, even two might work, but for blue or (modern) green LEDs, that might not be enough voltage to exceed the LED forward voltage and produce much light.  When the battery voltage is that close to the LED forward voltage, current regulation with a resistor ceases to work anyway, as the battery voltage would vary too much during the course of its discharge.  In that kind of case, say an high power efficient LED flashlight, more active current-regulating driver circuits are needed.