The phrase “how to create a JDBC” makes no sense.
You need to learn some basics first. Be clear on what JDBC is (a standard for connecting or mediating between a database and a Java app), what a JDBC driver is (a particular implementation of JDBC for a specific database.
There are four types of JDBC drivers, the Type 4 (pure Java) being most common in my experience.
For any particular database, you may find there are zero, one or more drivers implemented and available. Some are free-of-cost and open-source, some are not. For example, in Postgres there are two open source drivers, the classic one and a newer rewrite-from-scratch one, as well as some commercial products.
A JDBC driver is only useful when trying to connect a Java app to your database. That may be your own app you are writing, or a finished app you obtained such as a database-administration tool.
You must have a Java implementation installed on your computer, such as one from Oracle or from the OpenJDK project, or from another vendor such as Azul (Zing & Zulu).
You need to learn about the Java Classpath, the list of all the folders where the JVM will be looking for Java classes and JAR files. Read the Oracle Tutorial. The easiest way to go is to drop your JDBC driver JAR into an already existing folder on the Classpath, so you do not need to twiddle with setting the Classpath. For example, on a Mac you could drop your driver into /Library/Java/Extensions.
The JDBC driver sits between the database engine and the Java app. You do not install the JDBC driver into the database engine, such as your Questions mentioned, “install a driver in postgresql”.
[Postgres] ↔ [JDBC driver] ↔ [JVM] ↔ [Java app]
