For an explosion, you will need to use a multi_manager to trigger all the stuff to blow up. First, the objects that u want to blow up need to be func_breakable. Make sure u name them, numbered as well. Then u need to spread around some env_explosion in the places u want them to blow. Name them too. Now put in a multi_manager and name it something like 'explomm'. Click on Smartedit. Now u need to add all the explosions and breakable stuff. Do this by hitting 'Add', type in the name of the particular entity. The value determines how many seconds that entity will 'go off' when the manger is triggered. For example, if theres a computer (comp1) and u want it to blow up (explo1), then the explosion would be placed close to the computer. Then in the mulit_manager, put in comp1 and explo1 and give them the same values (for example 1). Then, when u set of the manager, these 2 will go off at the same time! Thats the VERY basic idea anyway, if you're still confused (which may be likely
) then post back and I may make u an example map...