When you make changes to your templates, your configuration settings, your category names, etc., you will need to rebuild your files to see those changes reflected on your public site. Note, however, that when editing an entry, or creating a new entry, you will not need to rebuild your files: editing and creating entries automatically rebuilds the archives for that entry, and updates all of your indexes.
When you do need to rebuild your files, log in to Movable Type, select your
weblog, then click Rebuild Files. You have the choice of rebuilding all of
your files (selected by default), or only your indexes. You will need to
rebuild all of your files if you changed any of your archive templates, or
if you changed configuration settings for your archives, etc. However, if the
only things that you changed were your index templates, then you will only
need to rebuild your indexes. Rebuilding your indexes is, of course, quite a
bit faster than rebuilding all of your files.
Note that rebuilding all of your files can take a good amount of time, particularly if you are using several different types of archiving; please be patient, and do not abort the rebuilding process.