Superblock - contains some general information about the filesystem such as:
The condition of the filesystem e.g. Would be marked as an error if the machine not shut down correctly and this would start the process of "fsck" on bootup.
A list of some of the free inodes and blocks available
Inode Table- which contains the number of inodes allocated to that filesystem. This is elastic in Linux and will expand if you require more inodes than those allocated. When you create a new file the kernel will allocate an inode for that file from the free list held in the superblock.
Data Blocks - containing the file data, a block is fixed in size. The kernel can only access the data blocks via the information held in the inode of that file.