Registered accounts can set several options in their profile like Name, Contact Information, Password and Avatar.
If the administrator has enabled custom user themes, you will be able to chose your individual design of IzzitUp that will be loaded when you log in.
Note, that several themes allkow for a dark or light menu bar. It is recommended that you use a dark navbar style for one of the darker navbar colors and vice versa. Play with the settings to find the combination you like.