Inline sources are easier than they appear. But they could use better explanation.
One constructs an inline source citation with three parts like this:
<ref name="a_unique_identifier">Your Usual Source Citation</ref>
- The reference tags <ref name="...">...</ref> which identify the information contained as a reference or citation.
- A unique identifier, a_unique_identifier, is a string of text that uniquely identifies the source citation. It's essentially giving a "name" to the citation, so you can refer to it later. For example, when I refer to a digital image froma microfilm of an 1832 baptism registration in the Quebec Catholic Parish Registers on FamilySearch, I usually use a name such as "1832_bapt_QPR_FS", which is a little more descriptive than "ref_1".
- Then you just need Your Usual Source Citation, which is however you would normally cite a source. e.g. I do a lot of copying and pasting of FamilySearch citations, but for other sources, I have a personal style. If it was that 1832 baptism, I would just copy and paste the citation provided on the microfilm.
To cite that source, you can place it at the first place where you want the first reference to appear. There are some different schools of thought on this, and I would recommend doing whatever most greatly facilitates the process for you, because it's more important to use sources and link sources to facts than it is to follow the dictates of any style guide. Personally, nowadays I construct a source list at the head of each profile.
Then, for each subsequent time that I want to invoke or reference that source as supporting a fact, I use a slightly different format:
<ref name="a_unique_identifier"/>
Note the extra forward slash character (/) before the bracket. That tells WikiTree that you are only referring to a citation which you have made elsewhere on the same profile.
Here's an example profile that I started 2 weeks ago, should you like to see a worked example of what I'm talking about: https://www.wikitree.com/wiki/St-Martin-60