Charles revealed there was no sense of panic in the Northern Ireland dressing room at half-time after O’Neill’s side drew a blank in the opening period despite their superiority.
Northern Ireland failed to break down the Belarusian rearguard when the sides drew 0-0 in their previous meeting in Hungary in October.
This time Ballard netted from a corner five minutes after the break, before Dion Charles converted his spot-kick in the 63rd minute after Kirill Pechenin was adjudged to have handled in the area.
“When we came in we said we couldn’t really let it get into that phase of the game where it slows down, then we scored quite early in the second half and we managed a second goal, so it was good.
“I wasn’t really concerned, we knew we could go out and score goals, we learned from the last time. Michael just came in and told us that we had to exploit certain areas to try and 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 take a step back and try and control it. We managed to do that 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 fixture 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 campaign and I think we’re well capable of doing it,” added Charles.