Hi and welcome to Boxerworld. You will love the site and all of the information it has to offer.
If you use the Search button for "crate" you will find a ton of information and suggestions on crates.
In our experience we bought a metal crate that we thought would be big enough when he grew up, but we were wrong. We ended up buying the biggest crate we could find. We feel better leaving him if we know he is safe in his crate and can't get into anything that could hurt him. It is also a big help in house training. Oscar is 14 months old and we still don't trust him alone in the house. He's an 80 lb baby that could get into a lot of trouble if he were allowed to.
Can't wait to see pictures of your new pup.
Myra