The lead source is used to track where a lead originated from, e.g. the web, print, showhouse, referral. Users can choose the lead source from the fields you configured here on contacts. Note, if you are part of a group your head office administrator can set lead sources and override it for all offices.
Add the main type, like Print and then add the subtype
You can create main lead source types with subtypes as illustrated here:
Example of selecting the lead source on contacts:
For groups: Set standard lead sources for all your offices
If you are the organisation administrator, simply go to general settings/parameters and set the "group: leads - user groups lead types" as checked. If you uncheck it, offices will be able to configure their own lead source types. It is recommended that you control this for all your offices for improved reporting purposes later on.