Think of
the staff as a ladder! We read from the bottom to the top, with each step (line or space) moving up in alphabetical order from A to G. When we reach G, we start back at A again.
For example, in the treble clef, the lines spell E, G, B, D, F, and the spaces spell F, A, C, E. Put them all together, and they climb up in order—E, F, G, A, B, C, D, E, F! Just remember, the musical alphabet only goes from A to G and then repeats!