Type or namespace 'Sqlite' could not be found in SQLite.cs
Follow this article to configure your project. Also explained here
Second you will need to go to the GITHUB website and download the code for SQLite-net-wp8. This is a c++ project you will need to access a sqlite database.
Make you sure you set Conditional compilation symbols: USE_WP8_NATIVE_SQLITE and release is x86 or ARM.
Tested on VS Profesional 2013, Release build (x86, ARM)
Go thorough bellow link
Windows Phone 7 Native Database Programming via Sqlite Client for Windows Phone
Hope it will help you