This kit is a very basic, almost "plug and play" kind of kit. It has an Arduino (of some sort), a servo shield (likely with the pins for each servo clearly defined on the silkscreen), plus an L298 module board and some servos. Plus the HC-SR04 (or something similar) ultrasonic sensor.
There are numerous tutorials and threads all over this forum and elsewhere (ie - instructables, for instance) which show how to use each of these parts individually. It's just a matter of taking each one at a time, learning it, then combining the parts together once you know how to do so. For instance, for the L298 board and motors:
The board may be slightly different - but with your board, the above tutorial, and a copy of the datasheet (and a multimeter - you do have one, right? If not - BUY ONE NOW) - you should be able to figure it out.
For the ultrasonic sensor and the servo:
Here - they aren't using an UNO - but they are using an Arduino (a Nano or Pro - one of the small ones). Alternatively, you could use some of the code and info from this instructable, perhaps:
...which is using an Uno.
Again - this stuff is basic - just take it one piece at a time; don't try to assemble the whole thing in one shot and expect it to work. Do one part, get comfortable with it, make it do everything you can think of, then move on to the next. When you have each part working, then move on to combining two of the parts, then more - until you have an assembled robot.
Also - as far as chassis assembly - the parts likely can only fit in one configuration - but if that isn't the case, get as many pictures from your supplier as you can, then google for more pictures to get an idea of how the parts fit together (ie - google "Smart Car Robot Chassis" and similar - will get you hits).