It's very easy
Goto "your sites" and then you can see a link to add new splash page - you can have 3 free splash pages.
Then, an editor will open up, and it's very intuitive.
You can write text, change colors and size
You can add images - You can add your banners with the html code and the HTML button - just paste it and update and then move them on the screen, add links to them and even upload gif animations.
Just give it a try and you'll see it is very easy.
Good luck
