Admins and mods have different post backgrounds when posting.
 

When making a post is it possible to have the admins and mods have different post backgrounds when posting... so you can see what level they are(Usergroup)

If you would like pictures to explain what I mean just ask.

Find the class tag of that td cell in your postbit and use a conditional statement to switch it around depending on usergroup.

So this would allow me to have the post bits like these:

I know these are phpBB but this is were I got the Idea from.
Admin:
http://www.freeimageups.com/files/1/Misc/admin.jpg
Mod:
http://www.freeimageups.com/files/1/Misc/mod.jpg
User:
http://www.freeimageups.com/files/1/Misc/user.jpg

So I need to make 3 different colors for the post bit dependent on there user group... Maybe more for future groups.

Kirby's code is a bit off... it should be <else />, not </else>. But you can use a condition around any of the table column classes you want to change. It may be easier to 'read' if you do it this way:

You'll need to do that for every td tag you want changed.

Can we alternate colour background on each subsequent post, within same usergroup?

I would guess so, but I think you would have to get a plugin involved then.

So this would be before every td tag in the postbit template ?

$post, X and $post, y would be the user groups?

and How would I make another alt# so I could have it on different styles

You would do that for every td tag that you wish to change. I've seen some users only want to change the post background and that would be here in red:
Make sure when you change it that all your <if> tags have a closing </if> tag.

x and y would be the usergroups.

To add another alt class, you would put it in the Main CSS for the style - at the bottom of that page.

now, as a secondary question to this, what if instead of changing the postbit BG I wanted to change just the admin or mod's font color, is that possible?

Sure, you can either just change the class or add the css for the color inline there.

If you just want to change the background inline, instead of adding a new class, just go:
(All just a thrown together example - don't use that code cuz I have no idea what you would produce!) Doing so for the font color would be similar.