It's infiltrate not conquer, when you press the initial attack button look for the infiltrate button and press that.
I know we've collectively mentioned this to you a few times now but you're also playing on the US servers and they have their own forum. For some reason when your googling for the forums you are getting diverted to here.
Forge of Empires Forum - The discussion board for all Forge of Empires players!
forum.us.forgeofempires.com
Most of your queries could just go in this section on there. As they're not bugs just issues with some mechanics and wording.
Ask Questions about FoE: (Remember to first search in the upper right corner)
forum.us.forgeofempires.com