1.) And we are off! Click the eye of your character. Goto Insert > Convert to Symbol.

2.) Now choose Movie Clip, and name your characters symbol eye. Click ok. Then double click the eye, and you will be in the eye movie clip.

3.) Now make insert keyframe on 15 and add a normal frame after it. Shown above left. Then on frame 15 you will make the eye blink so just delete what's on that frame and draw a slant, shown above right. There you go, publish your flash and watch toad blink.

4.) There you go, publish your flash and watch toad blink. Usually your character will always blink, so keeping this animation works, otherwise you have a character who's eye's never blink, which is unnatural.