The first step when it comes to assembling the tank is to assemble the turret. The missile launchers and cannons go in as shown. The second step is assembling the hull, with the upper and lower hull being assembled first, the rear hull part going in next, and the upper hull parts going in last.
The next step is to add the tracks and wheels, to install them you need to add the sprocket and return roller (the return roller is the first set of wheels near the front of the hull, not the road wheels) to the tracks first, and then install the assembly and it's wheels to the respective pegs. Installing all the wheels before adding the tracks will make it difficult to install them, so do this method.
The final step is to add the skirt armor, and then you're done!