This is actually two questions; “How do I create an account for my friend?” and “How do I make it secure with FileVault?” Once you go through the process of creating your friend’s account and securing it, I highly recommend that you turn on FileVault for all other user accounts on the computer.
Open System Preferences
Click on the Apple logo in the upper right hand corner of the screen and select “System Preferences.
Open Accounts Preference Pane
Click on on the Accounts prefernce pane icon.
Click the lock in the lower right hand corner of the preference pane to unlock it.
Enter the username and password of a user who has administrative rights and click “OK”.
Add New Account
Click the + button in the lower right hand corner of the preference pane.
Enter Username and Password
Enter the username and password you desire. Note that he Name can be as many words as desired. The Shortname can not have any spaces and must be all lower case characters.
Create Strong, Safe Password
Click on the key icon to reveal a password strength test tool called Password Assistant.
Check the Strength of Your Password
Using a combination of upper and lower case letters, numbers and symbols, create a password that registers at least 3/4 on the Quality bar. The more charicters the stronger the password.
Turn On FileVault
For added security, turn on FileVault protection. FileVault securely encrypts your user’s home folder so that even if the computer was stolen, no one can get to your data without your password. Without FileVault, anyone can access your files should your computer be lost or stolen.
If you are setting up FileVault for the first time, you will be prompted to set a Master Password. A master password allows you to change the passwords for FileVault users should they forget their passwords. It is VERY important that this password be set, with a very secure password (use the password strength tool by clicking the key icon if necessary) and that the password be kept in a safe place. If you forget both your FileVault account password AND your Master Password, you will not be able to access your data.
Time Machine Warnings
Because FileVault is so safe, you will only be able to restore ALL of the files and folders in your home folder.
Your Account is Created
You can see now that your new account is created. Go ahead and log out and log into your new account to test it.