If the problem is "find the perimeter" just find the lengths of the three sides and add them! The distance from to is . You are given the coordinates of the three points. Find those three distances and add.
and don't know how to find side lengths?
That's a bit like trying to cook and not knowing how to turn on the stove
Also, your diagram is faulty (if in 1st quadrant as the coordinates suggest).
I suggest the following:
1: change your labelling from 1,2,3 to A,B,C respectively
2: get some graph paper and plot your triangle correctly
3: come back with a new/correct diagram
4: show your work