I'll try to describe things as best I can...
I am assuming you have some knowledge of the Tell Target action and the If statement. Also, I'm simply giving you examples of how to make a health bar/tell if you've blocked a punch.
For the health bar, you need to use the Tell Target action. Create a movieclip of the health bar, and have it so in every frame a little more health is gone (so if you played this movieclip, it would show the health bar go from full to empty). Put a stop action on the first frame, and give the movieclip an instance name of health.
Now goto the button you'll have to click to punch the enemy. Give the button this action:
On Press, Begin Tell Target /health goto next frame.
As for the blocking technique, you'll have to use the If statement, and I'm gonna be rough on this one.
When you block, have an action such as;
Set Variable: "actions" = blocked
When you stop blocking, have an action such as;
Set Variable: "actions" = unblocked
..
Now, when the enemy takes a shot at you, have an action such as;
If ("actions" = "blocked")
Goto and stop frame 1
Else
Goto and play frame 2
End if
..
Of course, you'd have to fit this all into your own settings, as this is nothing but a general idea of how to do things. If I get my ftp working again I'll upload some sample swf's.