Don't quite understand the question but...
The script would go in the island.
If you have say some image files for the banner put them where ever you want.Then reference them in the script.
if it is a php script then you would place the php code between the comments in the island code.

It might be a better starting point with posting a banner ad you like and we all can make suggestions.

this is the kind i like to add

/* PHP CODE HERE */
# Le Pee H Pee
$Ads = array (
"http://www.asiabarhop.com/banners/LOLLIPOP1.jpg",
"http://www.asiabarhop.com/banners/lb_banner13.jpg",
"http://www.asiabarhop.com/banners/tequilareef_ad_468.jpg"
);

$adNum = mt_rand(0, count($Ads)-1);

# The body!
$body = <<<EOF
<img src="{$Ads[$adNum]}" />
EOF;


What am i doing wrong?????? am i not enabling it in ubb? i have enableled all that i can see to do

Hmm, that looks proper. You should now just be able to go into portal layout and choose where you want it to display.

I checked the links for your banners the 2nd one
http://www.asiabarhop.com/banners/lb_banner13.jpg
Does not exist I get a file not found.

i don't want it to go on lt side or rt side i want it to go between 1 & 2 post in forums

I removed the one banner that's why the one does not work

You have to make it a custom island first.
Then you would add the island at
Control Panel » Forum Settings » Edit Forum
TAB>Custom inserts.
Select the island from the list in the
Custom Island Insert field.

Oh forgot about this part.
After you do the above.
You need to make the groups see it by going to:
Control Panel » Forum Permissions
Must view Ad Island
Set a 1 in each group you want to make it visible to.