Welcome on ALL ABOUT CIRCUITS.
As Dave said a lot of information can be found here.
You can also use the search function of the forum to look if some queation has been asked before.
Another website with a lot of information on general electronics you can take a look in the EDUCYPEDIA. http://www.educypedia.be/electronics...icaopening.htm
If you have any questions, place them in the forum and we wil have a look at it.