Run a piece of paper, like a $5 bill, under the barrel up towards the receiver. It if stops or sticks before you get to the chamber area, it's not floated. The chamber area should be supported by the stock.
Floating a barrel is easy. Just sand the barrel channel where it touches the barrel to relieve that area. However, not all rifles like being floated. The only way to find out if your's does, is to do it after shooting the rifle off a bench. If you don't shoot it first, you'll have no way of knowing if the groups are improved or not.