Familiarize yourself with the layout of the TI-83's keypad. The graphing calculator differs from scientific calculators or other types of calculators in that it offers more options, including menu keys and function keys. Menu keys like "Mode," "Stat" and "Matrix" offer choices when you push the buttons; for example, you can press the "Mode" key to change from normal calculator mode to scientific mode, which will return answers as powers of 10. Function keys perform a particular function; for example, the "2nd" key acts like the "Shift" key on a regular keyboard: you'll be able to access the second row of letters and numbers listed above the regular keys when you press it.
Locate the keys you would commonly use for your class. In trigonometry and algebra, you might use the "Log" or "Exponent" keys. The "Log" key is located in the far left column of buttons, to the left of the "7" key. Use the "^" key for exponents; for example, press "5" and then "^" and then "2" for 5 squared. The "^" key is in the right-hand column, below the "Clear" button.
Look at the catalog if you can't find a key that will perform your needed calculation. The TI-83 catalog contains dozens of different functions. For example, you can find most of the keypad commands in the catalog including "Log" and "Ln," plus there are many commands not found elsewhere on the keypad like the 'Solve" function. This finds the root of expression for a variable, given an initial guess that you type into the calculator along with a lower and upper boundary.