The dot, when dealing with note value, will ALWAYS BE BESIDE THE NOTE, ON THE RIGHT SIDE.  This is a really important fact to remember, because dots can appear other places and mean different things.  All notes can be dotted. They can appear on ledger lines just like any other note:

 

No matter what kind of note it is, the dot will always do the same thing.  Here is the most important aspect of dotted rhythms:
 

The Dot- ADDS ½ (one half) of the note’s ORIGINAL VALUE TO IT! 

 
Let’s take a look at the whole note.  Below is a picture of what it looks like, and how you find the value:

 Original value= 4 beats    Dot=half value, which is 2 beats.   4 beats + 2 beats= 6 beats.  This means a dotted quarter note gets 6 beats total.
 

See, it’s not that hard.  If you apply the same equation to every note you get, then you can findthe value of every dotted note that you may see.  Here is a breakdown in pictures to help you out:

Original value=2 beats   Dot= half value, which is 1 beat.  2 beats + 1 beat = 3 beats
 

Original value= 1 beat     Dot= half value, which is ½ beat.  1 beat + ½ beat = 1 ½ beats
 

Original value = ½ a beat   Dote = half value, which is ¼ a beat.  ½ beat + ¼ beat = ¾ beat.
 

Notice that when you are dealing with dotted quarter and dotted eighth notes, that they have partial beats contained in them.  When you are dealing with partial beats, they generally have something after them that complete the count.  For example, the dotted quarter note is equal to 1 ½ beats.  Where is the other ½ beat?  It has to take the form of something right?  Most of the time, that space will be filled with an 8^th note.  An 8^th note is ½ a beat, right?  So that fills the space and you have complete counts.  Remember, your objective is always to have complete measures that stick to your time signature.  Here is an example of a correct measure using dotted rhythms:
 

 

The counts of this measure would be 1&2 - & - 3&4 - &  (1&2 and 3&4 are squeezed together since they are in the same note) 
 

See, this measure equals 4 beats if you add all the values together.  It is a complete measure.  Here is an example of a incorrect measure using dotted quarter notes:

If you add all the beats together in this measure, you get 3 ½ beats right?  There is a ½ beat missing, so it doesn’t equal 4 beats.  This is an incomplete measure and you can’t have this in music.  All measures must always be complete!  Stick to the time signature and you will always be right.

 

Dotted eighth notes follow the same rule.  Always make sure you have a complete measure and make sure your counts are right.  Here is a quick example:

The counts of this measure would be 1e& - a- 2 – 3- 4.  (1e& are squeezed together because they are the first three 16^th notes within the dotted 8^th).  The “a” is the remaining 16^th note that fills the space and makes the measure worth 4 complete beats.

 
 

Remember:  Always complete your measures according to time signature!