How To add 1 headphone and output speaker at the same time in my laptop

N5521? Could it be the Inspiron 15R 5521 model?

as im a dj i have to add headphones n output speaker 3.5 mm jack in the sametime

Do you need the same audio to go to both jacks at the same time, or different audio going to each jack?

If you just need the same audio to go to 2 jacks, you can get a jack splitter -- a Y cable adapter -- to create 2 jacks.

If you need 2 separate audio streams (different audio to each jack) and you have the software that can output 2 streams, then try this:

Open the Playback tab of the Sound Properties (right click on the audio icon on the taskbar and select Playback Devices), and set your speakers to be the default playback device and the headphone jack to be the "Default Communication Headphones". That is similar to what used to be called "Independent R.T.C. headphones" a few years ago. I am not familiar with DJ software but from old posts here I am under the impression that there is DJ software that can can send separate audio streams to the 2 devices when setup that way.

If that works -- with separate audio going to the 2 devices -- then you can add an external usb audio adapter to get the 2nd jack you need. You would set the usb device to be the default playback device and leave the headphone jack as the default communication device. However you would need the dj software to make it work. If you do not know of such software perhaps you can get some help on a dj forum.

If the setup described above does not result in 2 separate audio streams with the appropriate software, then I would guess that you need some additional hardware or a different model of computer. The dj forums should know if there is usb hardware that can allow the 2 audio streams that you need.