Integrate Login to my Application Android SQLite Database

i am trying add a Login Autenthication method with validation at SQLite database , but , someone could help ?

theses are the files of my project.

http://ift.tt/1K0ISVp

When i am trying Start the aplication , show me the error at:

LoginDatabasebaseAdapter

Line : 23

The message is :

" Cannot resolve symbol DatabaseHelper "

Someone could help me ?