How do I know if I am singing from my throat. WHen I sing and feel my throat, it vibrates slightly. Is this correct?
Yes your throat will vibrate as the vocal chords move. If you want to check that you are singing into mouth/nasal passages the easiest way is to put your hand in front of your mouth so you can feel the breath coming out. Put the other hand on your throat lightly. Now try singing from the throat, then think of pushing the air out of your mouth towards your hand ... you will notice more breath (not volume) and less throat vibration.
If you find you are singing from the throat... One way to stop this is to practice singing to the front (as I call it) is to sing consonants that makes your lips vibrate... such as br mm vv zz. Try to get your lips to vibrate as much as you can (practice will improve this and help you stop singing from your throat).