> How I make to pass the parameters indicating rolls it and the user,
> to indicate the type of isolation of the transactions saw jaybird?

If I understand you correctly, you ask how to tell in connection parameters
the default transaction isolation level, right?

In JayBird this is possible only if you obtain connections via
org.firebirdsql.pool.FBConnectionPoolDataSource or
org.firebirdsql.pool.FBWrappingDataSource data sources. See javadoc for the
appropriate setter methods.

However application decides itself which isolation level to use and it can
ignore your setting.

> Another thing, somebody knows as to pass the commands for creation of
> a DB

It is not possible to create a database in JayBird with SQL. You have to use
org.firebirdsql.management.FBManager class for this task. See javadoc for
more information.

> to create table tb saw jaybird.

Tables are created by executing normal CREATE TABLE statements via
java.sql.Statement instance.

Roman