Capacitor hook up question., XTREME 1.25 FARAD Options

[Snyper94GT]

I purchased an XTREME 1.25 FARAD capacitor. Upon opening the package I noticed that the capacitor had a + and - connection point. Most smaller capacitors only had a + in and a + out that I'd seen (never seen one for a system before). The directions were a bit confusing. Here's how I hooked it up a positive (direct feed from battery) coming in to the positive and a ground going to the -. I then took a connection from my amp which was the + lead to my amp and hooked it to the + part of the capacitor. I let it charge the capacitor and then started up my car. Yet now my lights still dim as if it's not even getting a charge reserve from the capacitor. Any idea's on if the is right or not. Any help would be great thanks!