Looks nice
To add hostages and start points you must add entities to your map. It's the "entity" button on the left toolbox in the Worldcraft/Hammer editor. Add one entity, then edit its properties. What will determine what type of entity it is is the classname.
The classname for hostages is hostage_entity.
For terrorists spawn points, it is info_player_deathmatch.
For CT spawn points, it is info_player_start.
You'll also need to add buy zones and hostage rescue zones, these are also entities but you don't add them the same way. You must create a big block box like you would do for creating a brush, then select it and use the menus to "tie to entity". Then your block will be changed into an entity. You will then be able to edit its parameters. Buy zones are func_buyzone's, and hostage rescue areas are func_hostage_rescue's.
And don't forget to add several light entities to your map also, else it will be way too dark to be playable when you'll compile it.
Good luck