Here is how to transcribe a recorded melody. First, you have to find the tonic (some people call it "do"). That's usually easiest by singing the ending. Now use a trick from sightsinging training: sing the tonic arpeggio: going up, 5 1 3 5 1 and now going down, 5 3 1 5 and finally going back up, 1. Now figure out which degree of the scale the tune starts on.
Now that you've got your starting note in your key, just go along by intervals. If your rhythmic transcriptions skills are not strong, just put notes without values at first, with the words of the song underneath, so you know where you are.
You can notate the whole thing in C major (or A minor) initially, if you're lazy about putting sharps or flats in the key signature.
When you're done, you can go back and copy the notes over again, but this time with quarter notes, half notes, ties, etc., etc.
It helps to listen through the whole piece while conducting. This will show you where 1 is for each measure.