Your question is not so clear, but let me give it a try!

Let's assume your 2 points are given as (x0, y0) and (x1, y1).
The x and y distances are given as:
dx = x1 - x0;
dy = y1 - y0;

The total distance is (Pytagoras):
d = Math.sqrt(dx * dx + dy * dy);

So, to move with constant speed from (x0, y0) to (x1, y1) you have to
define a speed, e.g.
speed = 5;

Let's assume your current position is given as x and y. For each time step, you apply
the following transform:
x = x + dx * speed / d;
y = y + dy * speed / d;