Graphing logarithmic functions on TI-84s isn’t much different from graphing any other functions. You just hit your “Y=” button an enter your equation.
The only complication occurs when you have a log with a base other than 10 or ##e##. To do this, just go to your “Math” key, and scroll down till you find “LogBase”. This will then allow you to have a different base.
Hope that helped 🙂