How to understand the effect of individual ingredients of recipes?
This is an overly broad question which may get closed by some here for that reason. For the future you may want to limit your questions to specifics goals or issues. It is often helpful to include what you have already tried.

As for general resources YouTube and other sites offer a variety of videos where experts will teach and demonstrate a variety of techniques. If you search Google or YouTube for "Alton Brown" and any of a variety of topics you are likely to find a video that will be helpful. Here is an episode from Alton Brown on Shish-Ka-Bob as an example.

Your profile indicates that you are in Pakistan, some of the best resources I can suggest come not directly from the internet but from television, much of which is also available via YouTube, Hulu and other internet sites. Also The Food Network website is a great resource.