The Guitar Strings
The first guitar string on the left of the guitar is the 6th string (Low E Note string).
The second guitar string after the 6th string is the 5th string (A Note string).
The third guitar string after the 5th string is the 4th string (D Note string).
The fourth guitar string after the 4th string is the 3rd string (G Note string).
The fifth guitar string after the 3rd string is the 2nd string (B Note string).
The sixth string after the 2nd string is the 1st string (High E Note string).
How to Play the Guitar
Your thumb is just labeled as "T" because you don't put your thumb on any of the guitar strings.
Your index finger is labeled as "1" because on the guitar, that finger is the first finger.
Your middle finger is labeled as "2" because on the guitar, that finger is the second finger.
Your ring finger is labeled as "3" because on the guitar, that finger is the third finger.
Your little finger is labeled as "4" because on the guitar, that finger is the fourth finger.