Read and Parse Dat file

I am getting a dat file with some records(no.of records vary each time). All records are of fixed length(400). If first two letters of arecord is HT then I need a datafield of length10 from position 5 to 24. If First two letters are CT then I need 3 data columns from different positions and length in that record. same applies for other two types of records. Depending upon first two letters I will need different dataelemnts to pull and insert into Database. Now I got struck up with how to read the fileand how to read each record of length 400 and parse it based on record type.

Do you know how to open a textfilereader to read a file?

If not, try searching google for "reading a file C# sample".