If you want to make something that explodes, make yer sprite and do this:
Look at its tile number and go to Defs.con. Put in define SPRITENAME 1234 (where SPRITENAME is the name of the sprite, and 1234 is the tile number). Then add this to game.con:
</font><blockquote><font size="1" face="Verdana, Arial">code:</font><hr /><pre style="font-size:x-small; font-family: fixed;">
useractor notenemy SPRITENAME
ifhitweapon
{
spawn EXPLOSION2 hitradius #Distance #Damage
killit
}
enda
[/code]</blockquote><font size="2" face="Verdana, Arial">(#Distance is the numerical distance and #Damage is the numerical damage rate).
Or if ya want to place one, do what Rott King said. If ya want to make one explode a wall, make the wall already exploded with a sector effector in it with a lotag of 13 and a unique hitag, plus a shrunk SEENINE with that hitag and a lotag of 1. Then give those explosive sprites outside the wall that hitag and a lotag to determine the amount of time before it explodes. If ya don't get it, i'll just e-mail ya a tutorial that revolves around explosions.