Talk to Konohamaru or the guy in the main town's ninja school to use the passwords. Unless you can read Japanese, you should consider the password entry menu a 4x4 square and one where you may input the following passcodes.
|--------------||--0--1--2--3--||--4--5--6--7--||--8--9--A--B--||--C--D--E--F--||--------------|
Use the above layout and press these symbols to unlock the following:

0 - F - D - E - 1 - 4 - 3 - 6 -- Kankuro unlock item.

2 - 6 - 7 - 0 - 9 - 1 - 4 - F -- Third Hokage unlock item.

7 - 5 - 8 - 2 - F - E - 1 - 6 -- Temari unlock item.

3 - E - 5 - 8 - 0 - 1 - 9 - F -- Gaara Unlock item.

9 - 6 - 3 - F - E - 0 - 8 - 1 -- Iruka unlock item.

6 - 9 - 7 - F - 1 - 5 - 3 - 4 -- Kyuubi Naruto unlock item.