The easiest way – to upload it all on your website, go to the bailiff and ask him to fix (to draw up the act of fixing the fact) the maintenance of the necessary pages of your website.
The idea is that the authorship arises from the moment of creation of the object, and you must decide how to claim about your authorship.
The act of a bailiff will not acknowledge that you are the author, but the date will be fixed and the object itself, as well as your website. Obviously, the domain name must also belong to you.
In the event of a dispute, in addition it will be necessary to prove that exactly you have done all that is fixed in the act. This is proved by source files, drawings, paintings, internal documents, etc. at the stage of creating the object.
If your object has the features of design pattern, then it can be registered in the Patent Office of the Republic of Latvia as a design pattern. In this case, you will receive a certificate confirming that you are the owner of this design.