Ok every time I play a song I see a SFz and those lines that are on the note some times there are more then one like in the song sonata by poulenc, and what does it mean when ther are 2 flats next to each other.

Sorry if I wrote to much.(:

Sfz means Sforzando and is just suddenly loud/accented for the one note.

Two flats next to a note means the note is double-flatted. A double Bb for instance is an enharmonic A.

http://www.sheetmusicplus.com/store/smp_inside.html?cart=33330491004029751&item=790362&page=01

And what are those lines in this song

I`m going to assume you meant the lines through the 16th notes. I forget what they`re called (quavers?), but they subdivide a note. So each of the 16th notes are really two 32nd notes (quartes becomes eights, eighths become sixteenths, etc).

The only other lines I see are:
tr~~~~~ which means the whole section is trilled.
8------- which means the whole section is to played an octave higher.

Heh heh a recording of the Poulenc just popped on the Flute List radio station too, still playing (live365.com).

On the Poulenc trills I`ve never heard the second note trilled... the trills stops right at the next note. Sometimes the ~~~~~ covers an entire section to be trilled. Here it`s probably just making sure you know to extend it right to the next note rather than ending early.

There are a lot of lines on that page. Some curved. Some short.
The ones on the 2nd staff from the bottom on the 16th notes indicate to double tongue. Play each note two times (Double tongue) - as if you are saying Tu then Ku.
If that isn`t the correct place, please define more specifically as to which lines you are referring.
~Bilbo