How do you kill the giant spider thing on the second place that you go..

So you mean you left the place you landed/started, the Impact Site where you got the Engine and now you're in the Forest of Hope? Well, I don't know of any Spider in the Forest of Hope, you must be in the Forest Navel. The Spider guy is actually called Beady Long Legs and you beat him by standing beneath/under him and throwing your Pikmin (preferably Yellow Pikmin because they go higher) up on to his round body. Avoid the legs, if you throw your Pikmin and they miss his body, they may go for his legs - so watch for that and Whistle them back if they do. When you beat him, you'll earn the Guard Satellite (use Red Pikmin to carry everything back to avoid the fire)...
Good luck gamebigs - you can do it =)

You have to go in front of it and a sucky thingy will go off, throw a pikmin into the thing and the back will open throw as many pikmin as you can in the red section and do that for a while and you killed the cocpit cover guardian

I think your talking about a beetle, not a spider, although it does look like a spider, you gotta wait until it is charging then throw a pikmin onto it, not a yellow because they well jump to high, and then it well open it's wings, throw both yellow and reds onto the wings, blues don't do as much damage, then call back your pikmin and do it again, but make sure your pikmin don't get hit twice by the rock, the first time they well get sucked into the ground so you can pick them later, so try to lure him away from that area. Dont worry if you lose many brave pikmin lives! The beetle itself gives about 50 seeds, so it's worth it!