Using Arduino Uno for triacs

I need help using an Arduino Uno to use triacs as an on or off switch.

Did you google "arduino triac"

If you are going to switch the AC power line you need an opto-isolator to isolate the high voltage from the Arduino. There are special opto-isolators for this purpose. The [u]MOC3010[/u] is an example.

The datasheet for the opto-isolator has a schematic showing how to wire it to a TRAIC.

In lower-voltage applications you can drive it pretty-much the same way as a transistor, with a voltage through a current-limiting resistor to the gate.

The 1st time I built something like this (for AC power) I tested it first with a 12VAC transformer and a 12V lamp. That's probably not going to prevent you from burning-up a component or two during testing, but there's less chance of a fire or mini-explosion, etc. "Spectacular" things can go wrong with a couple-kilowatts of available power!

Make sure you understand what are the risks of working with high(er) mains, line, AC voltage before you adventure into that.

If all you need is on/off and no PWM/fast switching, perhaps look at a relay driven by a transistor instead, much simplier.
There are readily made boards/module for that even.

A TRIAC is quite a bit more complex (zero crossing/snubber network plus optocoupler for safety) and proper cooling depending on its load.

If you're driving a small load and do not want the noise of a relay, look into getting a SSR (Solid State Relay)
Get the largest rated unit you can afford as I do not trust the rating on the usual chinese Fotek (and clones)