Charles revealed there was no sense of panic in the Northern Ireland dressing room at half-time after O’Neill’s side drew a first-half blank despite their superiority.
Northern Ireland failed to break down the Belarusian rearguard when the teams drew 0-0 in their previous meeting in Hungary in October.
This time Ballard scored from a corner five minutes after the break, before Dion Charles converted his penalty in the 63rd minute after Kirill Pechenin was penalized for a handball in the area.
“When we came in we said we couldn’t let the game get to that phase of the game where it slows down, then we scored quite early in the second half and got a second goal, so it was good.
“I wasn’t really worried, we knew we could go out and score goals, we learned from last time. Michael just came in and told us we had to exploit certain areas to try to score, so it ended up coming from a set piece, something that we had worked on.
“When you score it’s important not to sit back and I thought we did that. When we scored the second goal we knew we could step back and try to control it. We managed to do it well.”
Northern Ireland’s victory was their third in a row at home in the Nations League in Group C3 and they will now complete their campaign with an away game against Luxembourg on Monday.
A draw in that match would be enough for NI to top the group and seal promotion.
“Everyone wants to go there and get our first away win of the season and I think we are very capable of doing that,” Charles added.