Ok, that's kinda like asking someone how to build a car. It's such a broad scope, so many different things to do.
A very good start for learning VBA is to use the Macro Recorder.
1. Think of a task you want to write some code for.
2. Figure out how to manually do that task by hand.
3. Start the Macro Recorder - tools - macro - record new macro
4. Do the Task Manually
5. Stop the macro recorder. - tools - macro - stop recording.
6. Look at and study the macro you just created.
Then ask specific questions in the Forum about how to improve parts of that code.