Triplets are a difficult rhythm to grasp at first. Here are a few ways of counting.
A triplet is three notes in one beat:
You just have to remember that the first note of every triplet is a beat. The Blue numbers in the image are the beats. So in time, there can be 4 sets of triplets in one Bar.
One easy to count Triplets is to say the words: One - La
Lee In your head as you are playing them. If you want to
the phrase above it would go somewhat like:
One - La - Lee, Two - La - Lee, Three - La - Lee, Four - La-Lee