A database is a collection of tables which store information.

A Database Management System is an application/environment for creating, modifying and administering any number of individual databases.

For example:

MSSQL databases are typically managed using MS SQL Server Management Studio

MySQL databases are commonly managed using PHPMyAdmin

First you have to learn about databases yourself. Once you have done that you also need to learn how to teach. Then you are ready to start teaching people about databases. You start with the basics, like what a database is and what fields and records are. You teach people about data types. You show them how to use an actual database application and create a simple database. You show them how to do other things like sorting, filtering, creating queries, creating reports, creating forms and many other things. You teach them about more complex things, such as normalisation, relational databases, distributive databases, linking databases to other databases and other applications, administering databases, integrating databases with programs.. There are all of these and many other things you can teach. You may specialise in one area of databases.

The correct form is "databases." This is the plural form of the word "database" and does not require an apostrophe.

No. It is a spreadsheet application. You can do simple databases in it, but it is not designed to create complex databases like relational databases. To do that you would use an actual database application.

First you have to learn about databases yourself. You will need to know about Access in particular, but is important to know a lot about databases in general. Once you have done that you also need to learn how to teach. Then you are ready to start teaching people about Microsoft Access. You start with the basics, like what a database is and what fields and records are. You teach people about data types that Access has. You show them how to use te actual database application and create a simple database. You show them how to do other things like sorting, filtering, creating queries, creating reports, creating forms and many other things. You teach them about more complex things, such as normalisation, relational databases, distributive databases, linking databases to other databases and other applications, administering databases, integrating databases with programs. You have to be able to reference these things back to Access. There are all of these and many other things you can teach when teaching people about Access. You would need a lot of preparation, including exercises to give to your students. It can be borig for them, particularly entering the data, so you have to look for ways to make it more interesting. You can do that by getting them to create databases about something they have a particular interest in or knowledge of.