I got a little confused, I couldn't even get past the tutorial.
When you use "Attack" it open a short window with inputs for actions like "Slash attack". Either you mash your keyboard and execute as many actions as possible, either you read your skills to see what combo you need to perform so you can use the skill
"Light attack" for example need you to do a "Pierce attack" and a "Blunt attack"
Is it clear enough ?