Hi there! I'm fairly new myself, so I can't promise that I know it all. BUT I can tell you where to start...
There are "stickys" at the top of the listed threads when you click on the DISigns board. You will want to read through those before you request and DISign. Here are a few must-reads...
Creative Boards Welcome
How to ask for DISigns, tips, FAQs and guidelines
and Meet the DISigners
Read through the first two threads. Then you can go to the third one I mentioned (Meet the DISigners). All the DISigners are listed with their links. You'll have to go through those threads to see what they have created and find a DISign you like. This thread also tells you what each DISigner speacializes in so you can request the design from the correct DISigner.
I hope that helps a little bit. I'm still trying to figure it all out too. I do know that all the DISigners on here are amazing and do this in their "free time" because they love doing it. So, it's great that your looking into this now instead of last minute (like me!). And what an awesome surprise for your wife & child!! They'll LOVE it!
Best of luck!