When creating a backstory for a character, how elaborate does it need to be? Or can it be a fairly simple?  I'm not much of a story teller, and I am not sure how much is to much or to little.

It needs to be as long as you are comfortable with and the group/dm you play with.

I personally love elaborate backstories.  With the groups I play with, it can become a foundation for plots and threads between and through adventures.  It doesn't need to be a novel; a couple of paragraphs that tells everyone about you.  You can flesh out details as they become important.

On the other hand, an elaborate backstory can constrain you.  If all the interesting stuff happened in your past, what opportunity is there to grow in the future?  So a blank slate and filling in gaps on the fly can work just fine.  

Finally, sometimes a dungeon crawl doesn't need much to go on.  The character's birthplace and whether they were jilted at a ball isn't as important as swinging that sword.

Best person to ask on what is NEEDED is the DM.  They have a large say in how the story flows, so it is they that needs the most of a backstory to utilize it.

It depends on what you want to do and what the DM expects. If the DM has no requirements then something like this is just as valid of a backstory:

"I was born in a little farming village. I got bored. I became an adventurer."

This leaves a lot to be filled in which you can fill in as you need to. When you improv something just write it down and remember it - if you want it to be true, that is. 

However, the more the DM has the more they can use it for plot hooks and the more details they can provide on the world (like the location and name of that village, the politics of the area, etc). Being co-operative with the DM with your backstory: be it detailed or vague, helps involve the immersion and ensures it will work for that campaign world.

Rather than starting with a "story" you can just have basic profiles of family members and important friends with a basic sentence about your relationship to them. Think of an event that meant something. Do things like this help build a foundation of background facts that you can stack fluffy words and creative descriptions onto when you need to. 

If you're stuck, try Xanathar's Guide To Everything: it has many tables you can just roll against to build your character history - which you can then take as a roll, choose or just be inspired by. It can be a great way to build something and maybe even be surprised by your own character and this can "create" the character in your mind from an RP perspective far better than just deciding the basics of race and class.

Back-stories do not have to be elaborate affairs, as they are pretty much the "before adventure and excitement" part of your character's history. Most of the time it can even be just summed up with the background you choose for your character. Did you choose the Guild Merchant background? Your character grew up learning about merchanty things before adventure happened and he be came a character instead of some NPC shopkeep. Take the Folk Hero background? Your character did something notable before being swept into the life of an adventurer. Does it matter what? Not really, unless your DM wants to use it as a seed or springboard for later adventure content. 

my most extensive back story was made for a character in a 1st edition world, a whole set of people, documents, uniforms, affiliations.. curse that made him appear half black fured bugbear..etc.
For a character that I knew full well was going to be placed in a third edition world, tricked by his blue dragon father into trying to haul a legendary cursed chest. 
  ie tossed into another dimension.. 

For Blue half-drake with a "treasure-sense"; organizations.. that was REALLY Mean.

Thank you everybody for all the help and examples.