If you get the knowledge about following concepts, you will become an expert in QTP

VB Scripting Concepts
QTP Record & Playback
Data Parameterization
Actions
Object Repository
Check Points & Output Values
Synchronization
Transaction Points
Test Settings & QTP Options
Test Results
Descriptive Programming
Regular Expressions
Functions & Library Files
Recovery Scenarios & Error Handling
File System Handling
Database Handling

All the best....