To incorporate the BIRT engine to a 4gl-based application, you need to write your 4gl source code and create and style your report.
Here you can find some general explanations about how to create and style your report.
File → New → Other (or CTRL + N)
Refer here to find out how to specify JDBC driver URL (below, you get the generalized example of specifying the Informix URL):
jdbc:informix-sqli://<HOST>:<PORT>/<DATABASE_NAME>: informixserver=<IBM Informix instance name>;user=<user_name>; password=<password>
For a simple report without parameters, you need only to create one data set with the query:
For more complex reports with parameters, you need to create separate data sets for the query and the parameters:
In the simplest possible example - which supposes no reports - this step can be omitted.