Dot adds the half length of the preceding note.
The second dot adds the half length of the preceding dot.

These two measures are the same note value. dotted1

The third dot adds the half length of the preceding dot.

These two measures are the same note value. dotted2

More subdivided pattern.

dotted3

Combination of pitch, note value, tie and dotted note.

Now, you can read the score like this. dotted4

DOWNLOAD PDF