I have a trigger (see screenshot), and I want both events to be taking place at the same time to trigger the action. However, the action occurs when just one have the events have taken place. Clearly, I don't understand events, conditions, and actions very well. Could someone please clarify the difference between events and conditions, and provide me with a solution? Noob question, I know... :L

Attachments:

An event is an event that has to happen. A condition is a condition that has to be met while the event happens for the trigger to fire. Basically, you can have it so that the middle button being pushed down is the event and the selection is the condition - that way, if the selection is true while the button is pushed down it'll fire. Otherwise, if the unit being selected is the event and the button being pushed down is the condition, it'll fire if you select the unit while the middle mouse button is pushed down.

My editor isn't starting up and I'm too lazy to restart, so I can't help you with specifics, but this is the difference. Try to find a condition that does either of your two events.

Try to use Imageshack or w/e next time ^.^

Triggers in sc2 are linking themselves to some game mechanics. Imagine that everything has a list with triggers that are checked, if the mechanic does something (e.g. player presses middle mouse button, or a unit enters a location or a unit is created or a unit attacks or ...).
Then all triggers in the list are checked.

In sc1 every trigger would have the events with running every 2 game seconds and everytime a wait is created.

in short:
Event = when should the trigger be checked?
Conditions = the trigger shall run his actions when the conditions are met.