That's what this forum is for.
There are numerous tutorials on the WEB. Search for "Videopad tutorials." Be aware though that some are dated, using older VP versions.
If there are two audio tracks, both will be heard, unless one is muted. Muting can be applied to the entire track - with the mute icon at its left - or to a specific clip via the right-click method described earlier. Thus, if one clip or track is muted the clips on the other won't be affected.
In your case, you are muting the bad pronunciation segment on track one and adding the good one on track two, in precisely the same place -the fix below the original - on the timeline. An export will include both audio tracks. Track one will play right up to the muted clip. Track two will be heard there. Track one resumes after the fix ends on track two.