2d chess unit selection and movement

Hey guys,

in the moment I try to program a chess game. But after creating the board i stuck. I have one unit and i want to select it and change the position. So tried to implement a color change when i click on a field position or an unit. I used an solution from this forum but I messed something up and I could either change the color of the unit or the field position if i tried that both work together the game always selected the field position and not the unit. I deleted the approach and try to start new but I cant select the unit and then select a field to change the position. Maybe someone of you could help me with the problem but more important could also explain me which approach is this case the best for 2d turn based games and where I could find more information. My google search was not successful most of the advises were for 3d games and as a total newbie I want to stay 2d for the beginning. In the moment I have a GameObject ChessField with the script FieldManager it creates white and black tiles and one unit.

Thank you for helping :)

public class FieldManager : MonoBehaviour {

 [SerializeField]
 private GameObject tileWhite;
 [SerializeField]
 private GameObject tileBlack;
 [SerializeField]
 private GameObject unitPawn;
 int MAPSIZE =8;
 // Use this for initialization
 void Start () {
     
     createField ();
     createUnit ();

 }

 // Update is called once per frame
 void Update () {


 }

 void createField(){
     GameObject newTile;

     for (int y = 0; y < MAPSIZE; y++) {
         for (int x = 0; x < MAPSIZE; x++) {
             if (x % 2 == 0&&y%2==0 || x%2!=0&&y%2!=0) {
                 newTile = Instantiate (tileWhite);
             } 
             else {
                 newTile = Instantiate (tileBlack);
             }

             newTile.transform.position = new Vector3(x, y, 0);
         }
     }
 }

 void createUnit(){
     GameObject newUnit = Instantiate(unitPawn);

     newUnit.transform.position = new Vector3 (3, 1, 1);
 }

}