Transmission issues

Start from begining;;;last fall i did a start-up at a car show..had car on stands;;don't remember if was in "n" or "p" not sure but i started car..rap thottle a coupe times,,trans went into gear;;not sur if was in n or p but while running it fell into gear turning the rear tires and as it slowed down could hear noise in trans;;yesyerday at my first time with car ran though all gears on warmup;; pits got to staging to do a pass;;had in high gear to to do burnout but car would:not move until real high rpm and barley move..drop into low gear and it moved great then;;did burnout ok in low;;pressed trans break and backed car up;;staged;put into low;;lauch car and barely moving car again;;took off and shifted to high gear;;car still barelly rolling i taped on trans brack about half track then all sudden it took off;;what think would be wrong?be another month before can test car again and track 120 miles away;;