Read Text File To Dataset

with the help of the following code am able to read the text file
now i need to insert values to the datatable in dataset
can anybody help me on this regard

string path = Server.MapPath("Account.txt");
StreamReader sr = File.OpenText(path);
string contents = sr.ReadToEnd();
Label1.Text = contents;
Label1.Text = contents.Replace(Environment.NewLine,"<br>");
sr.Close();


how shall i spilt them and add each value to two fields of the datatable

for example i have the fields in text file as
Username1:Password1
Username2:Password2
etc
i need to add the username seperatelt to a field called username in table
and password in password field of the datatable
an example with code would be better and helpful

thanks
shruhti