One tutorial: How to make a simple castle wall without boolean operations
Okay, I admit it's a bit incoherent, but so ... "extrude" the key is E, "knife" is a key K, selecting and moving the mouse right button. Zooming and rotating the camera with the middle mouse button. The left mouse button you use only when you select items in the contextual menu or you confirm the action being performed. Toggle between Edit Mode and Object Mode you can do in many ways, such as the Tab key or the button at the bottom with the text Object mode, so there. For selecting faces use the three buttons that are placed on the bar below the 3D window. There are three dots, one line and a triangle with a dot in the middle. When doing any change, should you rotate with an object (key R), scale an object (key S) or move with an object (key G), you can use the middle mouse button to select the axis. The same is true when you're in edit mode and do these changes with points, lines, or faces. For flying with camera (Camera for render is key Num0) press Shift + F. I can not slow down the video, but if you need, you can pause it.