"I forget how to create user..." this usually happens when someone has too many tasks to do and he forgets things. The very intuitive navigation menu will help you to find how to create user. But if you want to be a professional SAP, try to memorize tcode. It's faster to execute what we want. Besides, perhaps you have heard this : "...You sow an action and reap a habit. You sow a habit and reap a character. You sow a character and reap your destiny...."** so, make action with tcode, and in the end it's your tcode destiny :)
**quoted from http://www.experiencefestival.com/a/Karma/id/22806