[rrd-users] Python-RRDtool

[Emily Chouinard]

I am a newbie and I am having difficulty running the example on python-
rrdtool. I have followed it word for word off the website 
>>> rrdtool.graph(path,
 	 '--imgformat', 'PNG',
	 '--width', '540', 	
	 '--height', '100', 
	 '--start', "-%i" % YEAR, 
	 '--end', "-1", 
	 '--vertical-label','Downloads/Day', 
 	 '--title', 'Annual Downloads', 
	 '--lower-limit', '0', DEF:downloads=downloads.rrd:downloads:AVERAGE',
'AREA:downloads#990033:Downloads')

and getting getting this error

Traceback (most recent call last): File "<stdin>", line 1, in ?
rrdtool.error: opening 'downloads.rrd': No such file or directory

I'm just lost and confused and really need a step by step. I'm a very
green programmer so if anyone can guide me towards tutorials and what
not I would really appreciate it because I need more information that
what I can find on the RRDtool website but I haven't been able to find
any. 

Thanks, Emily