Can I get Mountain Lion on a MacBook?
Probably not. The system requirements for 10.8 say "MacBook (Late 2008 Aluminum, or Early 2009 or newer)". You'd also need to install 10.6.8 or 10.7 first in order to install Mountain Lion from App Store.

See these Apple KB articles:


System requirements for OS X Mountain Lion
System requirements for OS X Lion and Mac OS X v10.6
How to identify MacBook models


EveryMac.com has a list of maximum OS X versions supported by different Macs:


http://www.everymac.com/systems/by_capability/maximum-macos-supported.html
http://www.everymac.com/mac-answers/os-x-lion-faq/macs-compatible-with-os-x-lion-hack-options-for-incompatible-macs.html