How to declare war?

I dont really know how to i have 117,000 soldiers and theres a country much weaker then me

I can't declare nor can I deploy troops

On the top left area of your country screen, hit the 3rd button, 'War,' then hit 'declare war.'

Where in the army or country map screen or the menu where you pick stuff

Under the tab that says War at the top. Select it and one of the options is Declare War.

Im on peaceful optinal war is this for anly worldwars?