The battery pack will look something like this:

http://www2.towerhobbies.com/cgi-bin...?&I=LXH333&P=0

and you should have a charger something like this:

http://www2.towerhobbies.com/cgi-bin...?&I=LXH359&P=0

I said "something" like this because I do not know what brand of radio you have but the basic physical shapes should be similar. The charger plugs into a switch harness like this one:

http://www2.towerhobbies.com/cgi-bin...?&I=LXH462&P=0

Good luck

What brand of radios are in your plane?