I thought of a perfect domain name for my site, but it has already been taken with the .com extension, there is .net, but i don't know if it is worth taking? Can sites using .net become as successful as a .com domain name?
.COMs are more valuable right now for a number of reasons and most people will say get a .com but I say if you really like the name then go ahead a get a .net. I own a number of .net domains that I want turn into long term businesses.
If the .net is still available, most likely it's not worth registering (simplistic rule of thumb, subject to exceptions). You can make a site successful with any extension of course, but you'll have to work harder with a .net. If you could perhaps share what the general image is that you wish your domain name to project, it would be much easier to say whether .net is a complete no-no or just a surmountable disadvantage in that specific case.
There are several successful dot net websites. If .com is not available the next best bet is net. SEO doesn't depend on extension. There are lots of dot info websites that are quite good. And for eyes sake lay off the color font will you please?