The first thing that'll strike you about ROBLOX is that it's a bit awkward.
If you need inspiration, you can look at other user's worlds or ROBLOX games they have created. In the online world, you can use various bricks to build whatever you want. There are two types of ROBLOX account – free and premium – and the privileges available to each obviously differ. To get the most out of ROBLOX, you have to sign up, which gives you a customizable character and a in-game real estate to play around with.
ROBLOX is an online set of worlds, built with a virtual Lego-like kit, that kids of all ages can play around in.