2005 Chrysler Town and Country Starter or Battery?

My van will not start. I have hooked it up to another vehicle to try and jump it with jumper cables. I even left them hooked up for over a half hour then tried to start the van and it would not turn over. However even when disconnected from the other car, the lights, power windows and locks still worked. I then hooked up a plug in charger, 12V 6amp to the battery and left it on there all night. When I tried to start the van in the morning, it would not turn over. After several attempts of starting it, the van would make a clicking noise so I stopped. However the lights and everything else still worked. My question is, I do not know if this means that the battery is going dead, thought I would have thought that it would have started via jumper cables even if the battery was dead, or if this means that it is the starter or alternator that has gone out. I am looking for suggestions on what may be wrong with the vehicle before I spend the money to tow it to a mechanic or just simply replace the battery. Funds are limited so any advice would be appreciated - thanks