As Klaus advised, you could take a look at the B4A User's Guide
In fact, I saw in your code that you want to use a separate jar file for opening the SQLite db file and you even don't require this : because the SQL library will open it.
So, the db file should be packaged with your app (Files Manager, Add File). Then when the app executes, because you can not access the assets files with SQL, you would have to copy the db file from the assets before to be able to initialize the SQL variable (File.Copy your db file, from File.DirAssets to File.DirInternal for example).