Ladies,
I recommend watching these Youtube videos:
Topic 1: SQL Injection
How SQL injections basically work – https://www.youtube.com/watch?v=_jKylhJtPmI
Running an SQL injection – https://www.youtube.com/watch?v=ciNHn38EyRc
Topic 2: Cross Site Scripting
Introduction to Cross Site Scripting – https://www.youtube.com/watch?v=L5l9lSnNMxg
Topic 3: Passwords:
Hashing – https://www.youtube.com/watch?v=7U-RbOKanYs
How to crack them – https://www.youtube.com/watch?v=7U-RbOKanYs
How to choose good ones – https://www.youtube.com/watch?v=3NjQ9b3pgIg
Basically, nearly all Computerphile videos are excellent.