1994 88 Royale, wont start occasionally

I have a 88 olds thats been sitting in my driveway since october, hasnt moved at all, and my park wrote me up for having it there so now I have to move it.

I dont know alot about cars, but when I got a battery for it last night, it had trouble starting at first, internal lights wouldnt turn on or anything, after playing a bit more with the battery, I just basically took off the pos then put it back on tighter, it started (with the volts light on), then shut back off and started again. It did that a few more tries, then it started running fine, but very loud. Usually the volts light would not turn on for a few minutes by now. I had my friend look at the engine and everything and he said I need to put brake and trans fluid in the car, so I waited till this morning to do that.

I didnt notice till after putting in the fluid, but my cars internal lights werent turning on again, and when I tried starting it, nothing happened.

The battery im using was bought in october and left in someones house till now, but it worked last night, and it isnt today. Should I just recharge the battery or is the problem deeper than that?

Update-

I got the car running...
As soon as I stopped listening to my friend and tightened the plugs in all the way >.>

Now it rumbles alot...I remember when I was driving it from the original owners house that it ran smoothly.

Soo, is there anything else? Could this be the alternator? My neighbor suggested to just take the alternator out and see if its that, but I dont wanna go there if I dont have to...