This is the UI (User Interface) you are greeted with when you boot up blender. At the very top it has a bar where you can do various actions such as saving your work. Beneath that you have another tool bar where you can select what type of processes you're wanting to do with your work.
If you select the modelling tool, this bar shows up on the left hand side of your screen. It has many tools what you can model your work with and help you create your desired design. Using these tools can help you change the shape of the your 3d model.
The top of the Gonk Droid.
The front and side of the droid.
The back and side of the droid.
These are the 3 main modelling tools within blender and the most commonly used. Extrude region does what the name suggests, it can make objects longer/wider by pulling them. Inset faces gives the object more faces and can often add some de3tail to make it look a lot better. Bevel can help shape the objects and add different edges and corners other than your regular edge and can make buildings or structure look a lot more complex.