when im 'racing' and i try to shift rather quickly in betewwn gears...my transmissions doesnt really like it

. second to third i can hit quick, same with fourth to fifth...but when it comes to third to fourth and fast shifting...it just doesnt happen. no matter what i do, i cannot get fourth quickly...i need to like leave the clutch on the floor for a sec or two...then put it in gear. so, after talking with others about this problem i was told that perhaps i should try changing my tranny fluid and see what that does. and after doing some searching...i could not find a nice DIY for changing tranny fluid. so if theres anyone out there that either has one...or could point me in the direction of one, itd be greatly appreciated. thank you.