I'm at a loss about how to propose a tag synonym.

The FAQs do a good job explaining what a tag synonym is, who can propose it and who can vote it.

Users with this privilege and a total answer score (total upvotes minus total downvotes) of 5 or more on the tag, can suggest tag synonyms. Users with a total answer score of 5 or more on the tag, can vote for tag synonyms.

This post What are tag synonyms and merged tags? How do they work? also clearly explains what tag synonyms are.

Now, I understand what synonyms are, but I don't understand how I can practically operate the UI to propose one.

By digging in the comments (not conspicuous!) of the linked post, and some other similar questions in here and on Meta Stack Overflow, I saw tips about clicking on the tag I want to create the synonym for.

English not being my first language, I have no idea what that means. I need to make a concrete example. Let's make an example from Chinese.SE, where I have more than 2500 rep:

I have finals and pinyin. Let's say I want to suggest a synonym that results in finals being remapped to pinyin. In other words, the tag finals will appear as having 0 questions; if I attempt to type finals in the tag bar, pinyin will show up instead.

In the UI I can navigate to a url like https://chinese.stackexchange.com/tags/finals/synonyms, and the page looks like the pic below.

The label of the input field reads:

Suggest a [finals] synonym.

This language is not clear enough for me.

If I write "pinyin" in that input field right there, will the outcome be to remap [finals] to [pinyin], or should I go the other way around?

Thanks