How do I charge my lawn tractor battery from a charger? Is red from charger going to red on battery?

Yes the red should be the positive and the black the negative.

If there are caps on this battery they should come off to charge. Charging can bubble the acid in the battery and build up pressure so caps off if you have them. To charge a battery safely with charger off hook up the red ( positive ) battery jumper. The ground off the charger does NOT have to go to the ground of the battery but can be grounded to the mower frame somewhere. Now the charger can be turned on.

The reason I say ground last and somewhere away from the negative post of the battery, there is a remote possibility that acid gass out of the battery area or exposed tops that can explode. But its so slim to none. I wanted to give it to you but the book. For jumping cars do the same thing except leave caps alone