To get crash logs from the device, please start iTunes, and connect your device to the computer via the USB sync cable. Select the device under the 'Devices' item in iTunes, then select the 'Sync' option.

To locate the crash logs, this depends on your system:
Windows Vista / Windows 7 / Windows 8
Files are located here:
C:\Users\*USERNAME*\AppData\Roaming\Apple Computer\Logs\CrashReporter/MobileDevice/*DEVICE_NAME*

Windows XP
Location is here:
C:\Documents and Settings\*USERNAME*\Application Data\Apple computer\Logs\CrashReporter/*DEVICE_NAME*

(NOTE FOR MAC USERS: ~/Library is hidden by default on Mac OS X. To easily get this folder, open the Finder application, then hold the "option" key while clicking on the "Go" menu. You should see a menu item for "Library." Click on that, then continue navigating to Logs, CrashReporter, etc.