1989 Buick Lesabre battery died

1989 Buick Lesabre Two Wheel Drive Automatic 290000 miles

I left my headlights on and killed my battery. I took it out because I thought I could recharge it in the house. Didn't realize the charger doesn't work with this type of battery. So I went to put it back in the car and can't get the positive post to go all the way in. It's got the positive and negative on the front of the battery where posts slide in. The positive is longer than the negative, plus there is a second positive cable. I don't remember taking two off, but my question is do I need to us both positive cables? Is that why the post is longer?