How to align objects to the center of another object I am new to Blender (2.8) and trying to model a kind of turret, to try and learn by myself. 

I am encountering a rather simple problem : I have placed 4 cannons relative to one another, and would like to align their center to the body of the turret (the grey elongated cube behind the cannons).

I would like to align them to the body of the cannon, either by :


Distributing them all along the length of the grey cube. (on the x axis)
Moving the cannons "as a whole" to the center of the cube.


I believe this should be simple, and has probably been answered before but I can't find where so I apologize.
The way to solve this is pretty simple: Select the objects you want to align, go to the "object" tab, and select "transform". This will give you another drop down menu, which at the bottom of is the option "Align objects". Select this, and a menu will appear on the left. It will show some options for aligning the selected objects. Play around with these settings until you have a pleasing result. You can also shift-click on the x,y,z align options to align on multiple axes at the same time.