Import your audio file into the audio editor and set the tempo of the project to match the tempo of the imported file. When you play the file back, each measure that passes should match up with the graphical layout of the project—meaning, as the playhead moves from left to right, it should reach a new measure marker at the same instant that each new measure starts in your audio file. Using the program's graphical layout is an important part of fixing the timing problems in your file.
Identify any problem areas that you want to fix. If a hit doesn't quite fall on the beat, for example, check the graphical markers at the top of the playback area and determine the location in the track where you want the beat instead of its current position.
Place the playhead just barely to the left of the missed hit, and then use your program's Cut or Split function. Now the original audio file should be separated into two regions.
Now place the playhead just barely to the right of the missed hit and cut or split the audio again. Now you have successfully cut the hit apart from the rest of the audio.
Click the region containing the missed hit and drag it to roughly the position where you want it.
Zoom into the audio with the program's zoom tool. This allows you to move the audio region with more precision.
Move the audio region until it's perfectly in line with the graphical marker at the top of the screen corresponding with the desired position of the hit. Now you've successfully corrected a timing issue in your drum beat.