I just played Mothership Zeta and beat the mission with flying colors. It was tough, but once you understand what the generators look like it's easy. If you need help with anything on Mothership Zeta reply to this thread. I will be happy to help you.

WHAT DO GENERATORS LOOK LIKE

MSZ done my nut in, it took me ages to find those damn generators.

how do i blow up the ship at end i keep shootin dontt know if hit

On the bridge where the death ray fire control is you have 3 other buttons (near the captains chair). One button puts more power to shields (so have your shields maxed out when the alien ship shoots at you), the other button takes power from the shield and adds it to the weopon which allows you to damage their ship faster. Remember to switch your shields back and wait for the enemy ship death ray to hit your ship after each time you shoot, then repeat the sequence.
You can set the shield and weopon evenly, that is fine too, it just takes more hits to destroy the other ship and you take a little bit more damage as well and might have to 'reset the generators' more than once throughout the fight. It is possible to end the fight without having to fiddle with generators to get the weopon back online.

For info there is a graphic of the ship by those battle controls that shows lines beside the death ray or over the hull of the ship, this indicates where you have power assigned to.

It's generally preferred that you simply review existing threads and answer/help out where you can, rather than having a topic of "ask me about this or that and I will answer".

And we do have a separate section for DLC related questions/hints and so on.