Basically a forum is not the correct way to start getting the hang of openCV. What I suggest you do is move over to the tutorial page, start at the top of the page and gradually move down to more exciting and more difficult examples. They are all well documented and give you example output that you should retrieve.
Once you got the hang of the basics, you could switch to some of the books that OpenCV provides which have OpenCV and C++ projects on different aspects of computer vision. The books can be retrieved on this link. I mainly suggest taking a look at the starter book and the practical project books.
Ofcourse once you have selected your problem and know the correct keywords, this forum contains a crazy amount of valuable information. Also, stackoverflow has a large community focussing on OpenCV problems.