There are 2 ways to apply entities, select certain ones from the
entity list when you press the icon and place them into map, or
for various other entities simply click on the object you want
to be an entity, and right click, then select tie to entity, and
there will be a big list of entities to choose from, im going
to list the essential ones:
info_player_start- your player start, needed in most maps for
it to be recognised,
info_player_deathmatch - obviously for dm
func_door - why am I listing these!
func_water - why!
light_environment - only need 1, only uses one, overall lighting
of map, if it has any sky
light - used for lighting up stuff :)
ambient_generic - used to put in such things as sounds
func_wall - can group objects together, such as complex shapes
and make them less laggy
a nice list of entity's and there uses check
handy vandal site.