Documentation for DataFrame is available at https://spark.apache.org/docs/latest/sql-programming-guide.html.
If you see any issues with implicit conversion, please double check to make sure you have included implicits import statement.
Example import statement for Spark 1.5.2
import sqlContext.implicits._
DataFrame is an extensive subsystem and deserves an entire book on its own. It makes complex data manipulation at scale available to SQL programmers.