The first symbol that appears at the beginning of every music staff is a clef symbol. It is very important because it tells you which note (A, B, C, D, E, F, or G) is found on each line or space. For example, a treble clef symbol tells you that the second line from the bottom (the line that the symbol curls around) is "G". On any staff, the notes are always arranged so that the next letter is always on the next higher line or space. The last note letter, G, is always followed by another A.
A bass clef symbol tells you that the second line from the top (the one bracketed by the symbol's dots) is F. The notes are still arranged in ascending order, but they are all in different places than they were in treble clef.