Open your preferred audio production program, such as Pro Tools or Logic.
Click "File" and select "Open Recent." Select the session to which you wish to add after effects. Click on the song or session title. It may take a few seconds for all of the data to fully load.
Identify the individual tracks that you want to match to the beat of the music by playing the track and pausing it when you hear a timing mistake. Rewind it and listen. "Solo" each potential culprit until you find the mistake. For example, if you hear an out-of-time horn, solo "Synth Horns" to check where the mistake is. The "Solo" function mutes everything but the selected track.
Click on the track that you want to correct. For example, "808 drums."
Click "Edit" and select "Quantize." This after effect automatically moves all "MIDI events" to the nearest beat marker. A MIDI event is any piece of information input via a MIDI controller. For example, you may have played in a drum groove using a MIDI drum machine. MIDI information is laid out on a grid. The vertical axis represents the instrument and the horizontal axis represents time. Beats and measures are illustrated by beat markers.
Select the "Quantize" ratio. Quantize can do many things, from bringing all slightly out-of-time notes into time to drastically overhauling the beat map of the entire groove. If you want to move every note to the nearest relevant beat marker, select the quantize ratio that matches the time signature. For example, if you are in standard time, select "4/4." If you want the quantize effect to spread out the beat so each note falls on a new measure, select "1/1." You can undo a quantize by pressing "CTRL+Z," so you can always experiment with different quantize ratios.