Finding

The first index position is zero.

myText.Substring()

Substring(int startPos) 
Substring(int startPos, int length) 

Retrieves a substring from this instance. The substring starts at a specified character position.
An index is the position of a character within a string, and is counted starting from the first character in the string.

string myText = "abcdefg" 

// remove the first character 
myText.Substring(1);                        // "bcdefg" 

// remove the last character 
myText.Substring(0, myText.Length - 1);     // "abcdef" 

// return the first character 
myText.Substring(0, 1);                     // "a" 

// return the last character 
myText.Substring(myText.Length - 1);        // "g" 
myText.Substring(myText.Length - 1, 1);     // "g" 

myText.IndexOf()

IndexOf(string value) 
IndexOf(string value, int startPos) 

Returns the index of the first occurrence of a String, or one or more characters, within this instance.
The IndexOf method is case sensitive
This returns -1 if the substring does not exist !!

string myText = "01/03/2004"; 
myText.IndexOf("/") = 2 
myText.Substring(0, sSomeText.IndexOf("/"));  // "01"