securing a flash drive(pen drive)

Hi,
I use a trekstor flash drive(pen drive). Does anyone know if there is a freeware program that encrytps a flash drive in a way

so that the user needs to put in a password each time they want to access files. It would be great if you could put in the

flash drive and the encryption would start up asking for a password even to allow you to view the files.

Any suggestions?

Thank you.

go to this website http://www.truecrypt.org/
that tels you what the program does then click on downloads at the top of the page then chose which os you have.

then there is a beginners guide here http://www.truecrypt.org/docs/?s=tutorial

hope this is what you are looking for

thanks pc_guy for your help in this thread and other threads.
much appreciated.