I'd start off w/ reading Guides on the forum to help fully understand the game before you just start off w/ any hero in a pub game to start new with b/c there really isn't a hero that's ideal to play w/ as a beginner.
Every hero has their own role and all have different play styles/item builds depending on what you're playing and who you're playing against.
What is important even as a beginner is knowing the character/hero roles, where/how to place wards/what they do, how to use a courier/what a courier does, how to lane/what to do.
Learning this early is always a + to increasing your chance in getting better and helping a team out.
Another way to learn and get better when you've mastered the basics is to watch some competitive games w/ higher level players and watch and learn how they play.
With the warding, the item builds, the skill builds, hero picks ect all which could be found here:
http://www.honcast.com/_____________
Useful Links That Might Help:
Premium Hero Guides:
http://forums.heroesofnewerth.com/forumdisplay.php?f=17Other Guides:
http://forums.heroesofnewerth.com/forumdisplay.php?f=53Warding Guide:
http://forums.heroesofnewerth.com/showthread.php?t=119117Laning Guide:
http://forums.heroesofnewerth.com/showthread.php?t=2625Read all of these / favorite if you want.
This helped me years back as a beginner.
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Hope some of this helped.