How to be confident without being obnoxious?

I lacked self confience too, but I read a couple of articals on wikihow about it.

Don't see yourself as inferior to others.
Talk about it with friends and loved ones
Remember that no one is perfect.
Identify your abilities.
Be thankful and possitive
Look in the mirror and smile.

Accept compliments gracefully. Do not show any attitude. Take it to heart and respond positively. "Thank you" or a smile works well.

for the rest of the artical, go here:
link

hope that helps :)