Let's say you have worked one long year and you want to change of archives...
Here's the commands I issue :
# create new archive
tla make-archive david.jobet@free.fr--2006-wiclear ~/archives/2006-wiclear
# make it new default archive
tla my-default-archive david.jobet@free.fr--2006-wiclear
# setup a new branch
tla archive-setup wiclear--dj--0.9
# make it a tag of my last commit of the old archive
tla tag david.jobet@free.fr--2005-wiclear/wiclear--dj--0.9--base-0 wiclear--dj--0.9
# create a mirror of my local archive on the net so that other can access it
tla make-archive --listing --mirror david.jobet@free.fr--2006-wiclear ftp://login:password@ftpperso.free.fr/wiclear/archives-2006
# and finally archive it
tla archive-mirror