(Beginner) How to provide power to a robot/car-kit with a Motor shield

Hello,

About two weeks ago I started learning how to use an Arduino. Since I am a starter (and have no experience with both electronics and programming) I ordered a Bluetooth Multi-Functional Car kit from China. Basically, this kit uses an Uno, sensor shield, motor shield, some sensors and 4 motors driving the wheels. Thought a kit would be a good place to start since then I just have to follow a manual, copy paste the code and then start to figure out other possibilities.

Unfortunately, the manual isn’t very consistent on how to power this car. Since I have no experience so I’m a little afraid to connect things. I understand that there might be useful information on Google, however I’m so inexperienced that I don’t really know what I’m really looking for. I’ll try to explain what I don’t understand (yet).

The kit came with an 18650-battery holder (2*3.7V) with a plug that fits directly into the Uno. The manual however, is showing that the power source is connected into the motor shield with an on/off switch in-between. I’d like to car to be turned on/off with the switch so I soldered two wires to the switch, but I’m not sure whether I can connect the power input directly into the motor shield. There are 8 cables connecting the motor shield to the sensor shield (I’ll add a picture of the diagram provided by the manufacturer).

So basically, I am unsure if it is possible to power the Uno trough the Motor shield which is connected to a sensor shield, and all that without frying anything. It probably depends on how the coding is done but the coding to me is like reading a foreign language that I have yet to understand. Unfortunately, I’m unable to post the coding directly, since it contains 11.167 characters (w/o spaces). I have added a link to the manual on the bottom of this post, the coding is on page 131.

Also, is it possible to replace the 18650 batteries with something else, like a 9volt battery or multiple AA-batteries? The 18650 batteries are pretty hard to come by, and don’t really feel like ordering them online if they are replaceable with something else.

<<<<<<PDF including the coding at page 131>>>>>>