It's very easy to use, you only have to choose a drive and create a virtual unit in it. That new virtual unit will be totally safe and passprotected, so you will be able to access it only if you know the password, if not, you will be automatically rejected.
TrueCrypt creates a virtual encrypted disk within a file and mounts it as a real disk, you can choose where you will create it, if you are going to encrypt an entire hard disk partition or a USB flash drive, It’s easy and safe.
Finally, we should stand out that the encryption is on-the-fly, so you won’t need to do extra actions, just save the data in the encrypted drive.
In addition, you can read a beginner’s tutorial here