How do you edit XML? i am trying to increase some weights but i can't affect the XML
events like the Dedicate the Obelisk one and what exactly do the <iWeight>400</iWeight> mean? (i am totally new at XMl stuff)

If you set <iWeight>-1</iWeight> then the event will happen as soon as prereqs are met (and every turn after that till obsolete). If you set it to 0 it'll never happen. The higher the number, the more likely the event will be.

You also have to modify the EventTrigger information to ensure that it is included in your game. The tag is <iPercentGamesActive> or something like that, and it is just that. Set to 100 and it is in every game, set to 0 and it is never in any game.