I put in the instrumental to help me with the beat mapping and timing, now i have finished i want to put the actual song in put i dont know how to? How do you put a new song into a beatmap that is already done?
Open the beatmap folder by clicking on "File" in the upper left corner of the editor and then selecting "Open beatmap folder". There you will find the audio file (mp3). Simply replace that file by moving your new mp3 into the folder and deleting the old one (I think you need to keep the same file name though). The offset might be different so make sure to check that