From literature to find the chain that already bund with ligand. Simultaneously also see protein in pdb viewer to find out the chain where ligand bund and also it's location of binding site? It help in geid preparation?

Have you tried to find information in the literature or in the Protein Data Bank (https://www.rcsb.org/)?

For this, you should have the 3D structure of the protein (X-ray or Homology model). The structure can be obtained from PDB or modeled at SWISS-MODEL. If the ligand is bound with a protein chain then you can select that chain for docking purposes. Moreover, if there are multiple structures available you can superimpose a few of them, and from a well-aligned cluster select the appropriate one. During selection, keep a few points in mind, for example, sequence of the protein is from a desirable source, resolution