The solution 1 given by
Lakamraju Raghuram is very good answer and straight to the point.
I want to add that, even if
pictureBox1.Location.X
can be modified, it is redundant in the following statement as the same value is again passed as an argument to the parameter of the constructor, which will be set in the constructor again.
pictureBox1.Location = new Point(pictureBox1.Location.X += 1, pictureBox1.Location.Y);
So,
pictureBox1.Location.X + 1
will be sufficient instead of
pictureBox1.Location.X += 1