There is no single or standard way to translate because there is no single way to program games, the way to translate depends a lot on the engine or programming language used.
The most common is that all the text can be imported/exported, that way, the creator can send you a file with some standard format, like .txt, .xml, .json, etc.
You pass him the file with the translation in the same format and he takes care of incorporating it into the game.
Depending on the engine or library it can be more complex, but you will have to talk about it in each case.
-Is it possible translating with no knowledge in programming?
Yes, especially if you are going to work with the creator of the game.
On the contrary, if you are going to do an unofficial translation, for example, translate the ROM of a SNES game, then you need more technical knowledge.
-How can I propose a translation?
Many people offer and/or request help in this subforum, including translations.
https://itch.io/board/10020/help-wanted-or-offered
If you are interested in a particular game, then it is best to write directly in the comment section of that game or contact its creators.