Welcome to the forum!
In addition to Alan's great advices, I strongly recommend to do not store the gun inside the holster, as the leather usually retains moiSture that can hurt the pistol finish, decreasing its value.
For disassembly,
youtube has several videos teaching how to do it.
Here is a couple:
http://www.youtube.com/watch?v=6LMPyQoHQzs (the interesting part begins at 3:25)
http://www.youtube.com/watch?v=3N3YEy-6qcE
And congratualtions for your decision to keep your granpa's heirloom in the family. Unfortunately, most of the people don't care.
All the best,
Douglas.