copy the object(s) in the map's .osu file and paste them in your map's then move them to the correct time if needed, or just directly edit the offset of the object(s) in the .osu to the right timeline ticks. wiki/Client/File_formats/Osu_%28file_format%29
also bpm and SV changes will need to match or you'll need to move objects and find correct SV multipliers to get it to fit.
Don't upload any maps where you copied other's work without that mapper's permission, especially full patterns or sliderart.