Oracle Exadata datafile distribution I'm new to Oracle and curious of how Oracle Exadata handles database files. Do we have to assign the disk to a database file as we do with Microsoft or is this handled by Exadata?
I do not know what you mean by the "Microsoft" way, but Exadata uses ASM.

Administering Oracle ASM Disk Groups on Oracle Exadata Storage Servers

http://www.oracle.com/technetwork/database/availability/maa-exadata-upgrade-asm-2339100.pdf

ASM is not specific to Exadata or any hardware, you can use it on any supported platform, even on Windows, so you handle database files just as in any other environment with ASM.