It's very easy. All you need is 6 wheels, two treads then get the side armor of the tank then the front and then the top and then the back. Everything needs to be made separately made in stages, and as LEGO tanks don't exist, it's entirely up to you how you design and make it.
There are a few videos posted on YouTube featuring Lego tank tutorials. SwissCheese707 demonstrates how to build a small tank. It is worth looking at the videos of the Brickologist, which include how to construct a model M8A1 Lego tank, as well as an AT-8 and a Panzer.
If you want to build a Lego tank, your best shot is to get some research from the Internet. Try typing 'Lego Tank' into Google images or just Google and see what it comes up with. As it is not an official set, there is not much more you can do. YouTube is also a great place for Lego step-by-step guides.
in a lego halo box or set
You need the buildings:training camp and the factory[I think]
get some Lego and then build it simple as
follow the instructions and build!
Unless you make it yourself, Lego Sherman tank does not exist. eBay is a great place to buy custom Lego models though.
To build Lego robots.
The Lego website has a Lego app that you can download to build different designs. The app is linked below.
You could try a site found below, I hope that helps. I've used it alot to build many things!
You get a bunch of legos and build it.
you play it after you build the rocket in the Lego Indiana Jones 2.