please suggest me some very simple tutorials explaning right from the basics of such functions .

I am doing C since 6 months and was looking at a tutorial of BEEJ's guide to network programming.. there at looking at a source code i found these functions and am really confused ...

I have already googled this topic but all the tutorials are getting above of my mind.

Help me!

I recommend going into a large bookstore, or one which specializes in "Technical books". Check the index of the "Advanced C programming" books, until you find an book with a whole chapter on signals, that also makes sense to you. If no bookstore is available, walk into someone's office that has a lot of books, such as a teacher or working professional.