I have a new site/idea and im worried a bigger competitor will steel my idea what can i do to prevent this if anything?
It's pretty hard to stop someone else doing something similar. If you think you have a unique process or concept, you should probably talk to a good lawyer to discuss options.
Copyright is very hard to protect in other countries - if someone likes your idea all they need to do is host the site somewhere that doesnt respect copyright. That said, putting a copyright on your site will help if your concept is unique. The only other idea is patenting (which doesnt apply to mere website content but does if there is an 'original process' or invention involved). Costs to get a patent though an takes time. If you have a genuinely original idea for a site the only real answer is to stay ahead of the competition by making sure it's polished to start with and then constanty improved..
I would like to know how I would prevent them copying my content OR my site. Is there any law protecting my site? If this happen being my back than does it affects my SEO efforts? What about DMCA filing?
Yes, DMCA is the way to go. Takes a little patience, but they fix things up real nice and clean. And OP, you should be worried about smaller blogs, not the bigs ones
Copyright only protects your content, not your idea. While copyright law protects the designs and code for sites like Facebook and Flickr, anyone is free to take the idea behind the site, a social network or image sharing site, and try to create a better site that does the same thing.
Copyright only protects your content. no way to protect your idea sorry man even laywer won't be usefull