This may sound really n00bish but...
just as the title says but how do u make military assets and Declare War and stuff
Look at the stickies in the II and NS forums and then buy military stuff from the various storefront threads. As for declaring war, you ought to build up a bit of a reputation first. When you do, make sure you RP a reason for going to war...there are no hard and fast rules.
I'm new to this too, but as far as I know, war is not like you may think. It is in RP form - in the forum - and you need to build up a reputation and population and stuff. You need to be good at stuff which is bad.
This should help you out a bit.
look in international incidents. there is an announcement there. it ends up telling you almost everything you need to know, and has links to many helpful things. read it all the way through and then ask any questions yu want on that thread. ill keep an eye out and answer them.