This is less than a simple problem if you give no information at all about the surface in question. If it is a single valued thing, so of the form z(x,y), where z is a SINGLE-valued function of and y. then you can use tools like scatteredInterpolant, griddata, or my own gridfit (found on the file exchange for free download.) Any of those tools will yied a surface. It will depend on how noisy is your surface, as to your choice of tool, since only gridfit will try to smooth the surface, to deal with noise.
However, IF your "surface" is something like the surface of a sphere, so a closed surface, then it is not single valued. In that case, modeling tools like those I mention above wiil fail miserably, since they presume a single valued relationship. In that case, you will be forced to use tools like CRUST, convex hulls, alpha shapes, etc.
But without even seeing your data, we can't really be more helpful. The crystal ball shows me nothing at all. If you want better help, then a picture can make thigns easier. If you want significantly better help, then post your data.
