When picking up a graphing calculator there are 4 items that you should check before you begin to graph.

1.) 2nd STAT PLOT:  Make sure all plots are THREE plots are turned off.  Remember there are only 3 plots.  On this menu number 4 will

 Try this so that you are familiar with it. See screen below.

2.) Y=: Check the Y= to make sure there are no equations in any of the Y=.  If there is you can 1.) Hit the clear button which will erase them or 2.) you can move the curser over the = sign and hit enter and then move the curser back to the right.  The = sign should no longer be highlighted which means the calculator will not graph the equation.

3.) 2nd FORMAT: Everything on the left should be highlighted

4.) MODE: Everything on the left should be highlighted.  REMINDER: When doing sine, cosine and tanget, you need to highlight Degrees instead of Radians

5.) Finally remember when graphing you always need to adjust the window to fit the data.