The only 25 pdrs are in your base. One at T2 and the second at T3, as Katitof stated. You do not have to manually add them.
To activate them, you need to activate the red smoke button which comes up with e.g. your infantry section
OK, thx. I guess I am a bit stuck in how the brits used to Work in COH1.
I have to say that the artillery is pretty disappointing in this version. This is hardly going to be a big issue for the WM.
What I like best about the UKF atm is all the speaks. As well the very british ('A splendid Cromwell has just arrived') as the ironic comments (especially understatements of hughe damage), the more rude comments and the swearing. You gotta love that.