Each component must be prepared in an assembly container
Although it is not mandatory, it is advisable or even very useful to prepare meticulously its assembly if you want a lasting result and easy to maintain in case of problems.
We will assume that each component is saved in its own file.
Three steps will need to be addressed here
How to create an assembly container ?
How to insert a component into an assembly container ?
How to create and organize the elements to be constrained ?
You can find the procedures on the video of the 1st example :