Its pretty much all HTML. You need to search for the nesecary hacks/add ons that give you your desired information such as all that info on the far right. Once you have these they are usualy a line with a variable in it such as this
PHP Code:
This is a test board its name is $name please visit
Where $name would contain the board name etc.
All of these basically get places in the table and are seperated by a
tag which moves too the next line.
In the code for the welcome panel try to find the writting in the template, where you wanted to add something.
Lets use your screenshot as an example.
Say that was your forum and you wanted to add something underneath where it says Total Posts Today on the far right hand side.
You would open the nessecary template and find the writting that says this, then simply add what you desire under it. Its meerly a case of trial and error im afraid.
As for the graphics etc around it, thats not my department sorry
Hope this helped a little, if not just say so and ill try my best to explain clearly.