Facebook Connect for 4.2.1?
 

What is the best one and how do I make it work?

Thanks all.

See ... Admin Control Panel --> Settings --> Options --> Facebook Options.

saw it I am at navbar and it says <if condition="$show['member']">
but my says <vb:if condition="$show['member']

because I have to insert something before it

Not sure what this has to do with facebook connect?

So what-ever template code conditional you are looking at: What you referring to is vb3 template conditional vs vb4 template conditional. Should be fine.

I downloaded fbconnect-3.0.5 for 4.2.1 and I am stuck on navbar

this is what I have Template: navbar

Find the first:
<if condition="$show['member']">

Insert Before:
<!-- fbconnect -->
$fbconnect_button
<!-- / fbconnect -->

But I have this is the navbar<vb:if condition="$show['member']

Or am I using the right one?

Facebook connect is built into vbulletin4, you should not have loaded that modification. Just disable it (Do Not Uninstall It <--> unless you know what you are doing.)

Then check the ACP (Admin Control Panel) as I posted above and setup your Facebook application. :)