I assume that you have mybb "conditional template" installed if don't download mybb conditional template.
First lets create mybb guest message that will only be visible to guests and only on index page.
Go to your admin CP-->Templates & Style-->Templates-->Your Template-->Index Page Templates-->index.
Inside the index template search for "{$header}" then add this code after "{$header}"
<div style="padding: 1em; margin-bottom: 1em; padding: 1em; border: 1px solid #cc3344; border-radius: 5px; color: #000; background-color: #ffe4e9; margin-bottom: 1em;"><h3 style="padding: 0; margin: 0;">Welcome Guest</h3><p style="margin: 1em 0 0 0;">Add some description here</p></div>
The message will look like this:
This code will show be visible to all users, to make it show only to guests we need to use mybb conditional template.
<if $mybb->user['uid'] <= '0' then></if>
Now the final code to use is this:
<if $mybb->user['uid'] <= '0' then>
<div style="padding: 1em; margin-bottom: 1em; padding: 1em; border: 1px solid #cc3344; border-radius: 5px; color: #000; background-color: #ffe4e9; margin-bottom: 1em;"><h3 style="padding: 0; margin: 0;">Welcome Guest</h3><p style="margin: 1em 0 0 0;">Add some description here</p></div>
</if>
Now to show this message across the whole forum board to guests only!
Go to your admin CP-->Templates & Style-->Templates-->Your Template-->Header Templates-->header.
Inside header template search for "<navigation>" and add this code above it!
<if $mybb->user['uid'] <= '0' then>
<div style="padding: 1em; margin-bottom: 1em; padding: 1em; border: 1px solid #cc3344; border-radius: 5px; color: #000; background-color: #ffe4e9; margin-bottom: 1em;"><h3 style="padding: 0; margin: 0;">Welcome Guest</h3><p style="margin: 1em 0 0 0;">Add some description here</p></div>
</if>
All these messages are only visible to the guests, however if you want to show these messages to registered users only, then use this code for the same templates!
<if $mybb->user['uid'] then>
<div style="padding: 1em; margin-bottom: 1em; padding: 1em; border: 1px solid #cc3344; border-radius: 5px;color: #000; background-color: #ffe4e9; margin-bottom: 1em;"><h3 style="padding: 0; margin: 0;">Welcome Guest</h3><p style="margin: 1em 0 0 0;">Add some description here</p></div>
</if>
To hide whatever you want from guests use this code:
<if $mybb->user['uid'] then>
YOUR CODE HERE
</if>
To show whatever you want only to guests use this code:
<if $mybb->user['uid'] <= '0' then>
YOUR CODE HERE
</if>
This version is for all of you that don't like to use DIV style and would rather use DIV class.
<div class="board_messages"><h3 style="padding: 0; margin: 0;">Welcome Guest</h3><p style="margin: 1em 0 0 0;">Add some description here</p></div>
Add this CSS code to your global.css file!
.board_messages {
background-color: #FFE4E9;
border: 1px solid #CC3344;
border-radius: 5px;
color: #000000;
margin-bottom: 1em;
padding: 1em;
}
This is called "mybb conditional template" which allows you to do amazing things it just one of those things you have to have!
Thanks