Hi, I'm trying to make an intense space battle where the objective is to destroy all enemy ships with cp's. I'm also trying to figure out how I'm gonna make multiple frigates as a separate objective. Can I get some help with this stuff. Thanks.

Have a look at all the stock space missions, as they will likely have the answers to your problems.

spa1g_c.lua in \assets\scripts\SPA has some useful info for the second.

Sorry but I still can't figure it out.

so what?
you must tell use with which parts exactly you have problems. nobody will script an "intense battle where you have to destroy many ships with and without cps"

I want to add more frigates to the frigate objective; and for the capitol ships I'm gonna make them destroyable but I want the regions and the cp's to be deactivated. But for the frigate mission, I want it to be an optional mission. My biggest problem is I don't know what LUA to put it in, where, and how.

then you should probably read the documentation that comes with the modtools and browse through other threads discussing campaign/lua scripting because you cant learn programming from one day to another.
once youve understood how everything works you will know yourself how to achieve these things yourself.
(and as long as you havent understood how it works you will encounter countless of problems)