The present study, using first principles, studies the structural, optical and magnetic properties of single-layer tungsten diselenide doped with elements of groups VIIB, VB, VIIA and VA. Analysis of the electronic structure of these materials shows that the systems doped with group VIIB exhibit p-type semiconductor behavior, while the use of elements of group VIIB changes the nature of the material to n-type semiconductor. In addition, in both cases, we will have a structure with a tuned band gap energy. In the case of nitrogen and fluorine impurity atoms, the simulation results indicate that the transmission spectrum is asymmetric for the high and low spin states, which indicates the semimetallic nature of this structure and its magnetic nature. Also, optical studies show that the doped structures with a semiconducting nature have the first imaginary maximum of the dielectric function equal to the band gap energy of the material. The results indicate an approach for tuning the electronic, optical, and magnetic properties of two-dimensional materials, especially tungsten diselenide, for many applications in the fields of nano, optoelectronics, and spintronics.