[urq] help me?

[Andrew B]

Foolishly I had my car out last night, and while I was out, my heater
stopped heating, and about 150 feet from my apartment, the car stalled
and refused to start.

When I turn the key, I hear nothing, then click....click....click...
once every 5 seconds maybe?  It comes from behind the dashboard
somewhere, or at least sounds like it.

I checked under the hood, the oil looks ok, from what i can tell. 
It's extremely clean, so it's difficult to read, but I just had an oil
change.

The coolant was extremely low, and this leads me to believe it
overheated.  I don't have a coolant gauge, yet.  I ran across the
street and filled up the coolant overflow with some antifreeze, but
still nothing.  I waited, and still nothing.

What is going on?  What could be wrong with it?  Could it be my
battery again?  Something with the coolant system?  When I got my oil
changed, the mechanic checked the level and told me the freezing point
was a little high.  Last night there was nothing in there!?  Could the
snow have knocked something loose?

I haven't tried starting it today, but I might later.  Maybe if it's
cooled down, it will turn over?  Should I get a new battery or
recharge the old one?  Jump starting will be difficult given the
conditions.

Please help, otherwise I might have to have it towed to the audi
dealership to what's wrong.

-Andrew
PS.  ARGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH