Creating flash buttons is one of the simplest ways of creating buttons. The reason its so easy is because once you have a general button that you want to apply states to you simple convert it to a symbol and flash brings a easy to use template where you just change the states.
Step 1
Firstly create some text like below of a button that you will need. This can be on the main timeline. I have renamed the layer link.

Step 2
Click on the text and then click F8 this will convert the text into a symol. Select the button symbol as showed below. Once this is done it will appear that there is no change.

Step 3
Double click on the text and it should open in the button symbol editing mode.
States
| Button State | |
| Up | The up state is what the button looks like before the user would rolover the object. |
| Over | The over state is what the button looks like when the mouse is over the button |
| Down | The down state is the button whilst the user is clicking on the button. |
| Hit | The hit is the area that defines when the button states shows. |

Step 4
To insert an over state click underneath "Over" right click and insert a keyframe. Then you change the colour, position add an image or whatever you wish to your button. I have simply added a line and change the font colour.

Step 5
For the down state i create another keyframe in "Down" section. This time i have selected the line and the text and nudged them to right and down so that when the user clicks it appears to be pushed in.

Step 6
As mentioned before "The hit is the area that defines when the button states shows". So simply draw a box or circle where you want a user to to be able to click on your button. This isnt visable so it doesnt matter about colour.

If you click control and check the "Enable Simple Buttons" it will allow you to test your button in the workframe. Alternatively you could click F12 to preview your button.