I have this wave amplifier of 64db max and an omnidirectional antenna of 3.2db and I have to transmit a sine wave of 82Mhz, are they suitable for me? What is the maximum gain I can get? I need at least 82db, how can I amplify the signal?
64dB(What)? dB is a power ratio so unless you say what your reference is, 64dB is meaningless except as a pure gain.
If your amplifier is good to 64dB reference to whatever and you need 82dB (referenced to the same thing) then you clearly need +18dB of gain (Plus whatever the feedline losses are) from the antenna, at 82MHz that is going to be a physically VERY large antenna.
You amplifier is an INSANELY expensive way to get power there, and looks to be good to about 1500W @ 82Mhz to me, I make 1,500W equivalent to somewhere around +31.7BW, or +61.7dBm (same thing, different reference level) adding 3.2dB of antenna gain gets you an (along the maximum power axis) EIRP of 31.7dBW + 3.2 = 33.9dBW, but you need to allow for feedline and connector losses as well...
Really you need to hire an RF guy, firstly to come up with a system design suitable to do whatever it is you are really trying to do, but also to advise on legal issues and shielding.
Finally you need someone who gets high power RF and how to handle it or you WILL end up either with destroyed equipment, fire or very nasty RF burns.