xterra won't start security problems

hi, i just bought a 2003 xterra and the battery was bad. i bought a new one and put on it and now it won't start. the security lights on the outside blink on and off. i repeately used my remote to lock and unlock the doors and the security lights go out. i then put the key in the ignition and try to start it and the security lights start flashing again. can anyone tell the how to get it started. my nearest dealer is 60 miles away. thanks wildturkey