http://www.bobrowconsulting.com/t/ArchiCADForCadManagers.pdf
Although a bit dated, this has infomation on setting up a template file. Probably a little more involved than you were expecting, though.
Also, if you look around, there are a number of predone template systems available, from free to, well, not-free.
http://v3.digitalvis.com/pdfs/offstand.pdf has some good info, too.
Do a search here on on "template" and you'll probably dig up a lot of useful information.
Richard
--------------------------
Richard Morrison, Architect-Interior Designer
AC26 (since AC6.0), Win10