Read a string from a stream

i can't read a string from a file stream or from a file then have the position in the file  

here is some code i tried 

StreamTry := TFileStream.Create('Key2.txt', fmOpenRead);

for I := 1 to 17 do

StreamTry.Readbuffer(Test[i],1);

for I := 1 to 17 do

Tryin := Tryin + Test[i].ToHexString;

please any help would be great thanks