you can do this, on two way :
First:
string A = "Username:Password";
string Username = A.Substring(0, A.IndexOf(':'));
A = A.Substring(A.IndexOf(':') + 1);
string Password = A;
Second:
string A = "Username:Password";
string[] Items = A.Split(':');
string Username2 = Items[0];
string Password2 = Items[1];
2
solved Reading TextBox List in C# [closed]