Importing VSys Live settings is slightly dangerous: this overwrites existing settings without prompting you for the individual things it's importing. As with many things in VSys, it's a very good idea to make a backup just before doing this.
Select Import settings from the VSys Live sites and settings tool, then select the file that you exported or were given.
VSys Live Sites
Only the sites you select here will be imported. You can safely import all, none, or some subset of the sites because individual VSys Live sites do not link to each other.
Items to import
For each site that you import, you can bring in all attributes of that site or just some. These can be Agreements, Application forms, Calendar items, and others. You can't selectively import some items from one site and a different set for another site in one pass; if you need to do something like that, import the individual sites one by one.
As above, importing some items and not others can cause the relationships between items to be broken.