You need to find out first whether the battery is good or not,and also if the system is charging.
If you don't have the means/tools nor knowledge to do it,have the battery checked out. If it's bad,replace it,see if the tractor will start,then before running it too long,check the charging system. If you have a voltmeter,with the engine running,it should put out from 13.5 to 15 volts. Any thing lower then that will tell you the system isn't charging properly.
It must get boring preaching to the choir.