need new variable for template

[Bilderback]

I am trying to create a custom php variable using the $userinfo[field5]

In my custom page, I reference a url relying on the members entry of field5

I have tried to create $customvariable = $vbulletin->$userinfo['field5'];
in my custom vbulletin php page but apparently I am not including a file or something.
(custom page currently only includes the global.php)

When I add $customvariable to the template, it doesnt display.
What am I missing?

thanks

EDIT:
What I am trying to accomplish is converting any spaces from the field5 entry to +characters.
example:
user entry: Hello World
conversion: Hello+World