Client Menu Reference : The Metadata Menu : Assign Categories
   
Assign Categories
Assigns a selection of records to a selection of categories, or vice versa. (This is the opposite of “Detach Categories.’) (Available only, if you are allowed to modify records.)
NOTE: If you have a large number of records (more than 500) you want to assign, it is better that you use this function rather than drag and drop.
 
1. Select one or more records.
2. Select one or more categories to which you want to assign the selected records.
3. Select Metadata > Assign Categories. The records are assigned to each of the categories in the selection.