[un_pogaz]

@hhtmp88 The functionality you're probably looking for is in "Tool>Table of Content>Edit the Table of Content".
However, each entry will have to be entered manually. It is possible to ease the work with the button "Generate the Table of Content": Sigil will search all Title tags <h1>,<h2>... and will create a default Table of Content.

@SigilTeam Eh, a good idea would be to add in the window "Edit the ToC":
A "Regenerated the ToC" button, with automatic default generation.
A "Added all XHTML files" button, which will index with brute force. I find that this feature is sorely lacking.
Possibly a "Mixed generation" button, which would be a merge of the 2, a merging the two.

EDIT: Actually, if you put the "Regenerated the ToC" in the "Edit the ToC" window, that would be great and probably better than today.
Currently the only big button in the UI dedicated to the Toc is "Generate the ToC", which will overwrite all preliminary work. For me, the logical choice would have been "Edit the ToC" (besides, the button next to it is "Edit the MetaData").