There are a good number of tutorials linked at the top of the forum. http://nch.invisionzone.com/topic/23872-videopad-tutorials/
Video on video track 1; audio on audio track 1. Slide the contents of either track until they sync at the head of the song. If sync drifts out as the song progresses this may be due to different speeds of the recording devices, if they weren't sync-locked together.
If more than a single video track, keep in mind that higher numbered tracks take precedence. In other words, if there is video on track 2, overlaying track 1, then track two will be seen if it fills the screen. If it does not, then track 1 will be in the background - picture-in--picture. Various effects can position and scale video as desired.
Do your best and if it isn't right please submit the project here. Someone will check it out and give you tips.
Don't submit the export, but instead create a PORTABLE PROJECT folder to upload. Follow the portable project instructions here...
http://nch.invisionzone.com/topic/23659-tips-for-getting-help-on-this-forum/
If it contains sensitive material link it in a personal message (PM). Click the envelope above. It won't be passed on or retained. Use FILE|SAVE PORTABLE PROJECT AS, not simply SAVE PROJECT, and don't forget to share it.