Update README.md

Author: Defelo

README.md

@@ -1,3 +1,21 @@
 # PassSHAfe
 
-An offline SHA-256 based password safe
+PassSHAfe is a deterministic HMAC-SHA-256 based password safe. It does not store a password database anywhere and you 
+only have to remember one master password. To access a password for a specific account you need a unique account 
+identifier. It is very important that you choose unique identifiers for all your accounts and that you can remember 
+the identifier. For example you could always use "\<URL\>:\<username\>" as your account identifier. For your master 
+password you should choose a really strong password. If you think you cannot remember your master password then write 
+it down and put it somewhere safe because if you forget your master password it is impossible to access any of your 
+account passwords. So make sure to choose a secure password and keep it somewhere safe.
+
+## How to use PassSHAfe
+1. Go to https://defelo.github.io/PassSHAfe/
+2. Enter your master password
+3. Enter your account identifier
+4. Change your password length (optional)
+5. Press Enter to copy your generated password to the clipboard
+6. Lock the safe
+
+## Download PassSHAfe
+You can always download the latest version of PassSHAfe here: https://github.com/Defelo/PassSHAfe/releases
+