1. Begin building surfaces that adjoin the primary surface.
Surface continuity is important your the modeling process. That is why you should try to model surfaces from existing surfaces whenever possible. Alias provides many tools that help align surfaces. One tool that should be used prior to any surface building is "Project tangent". To use this tool, you should have a curve that is built off of an existing surface. Select that curve, then select Curve Tools-> Project Tangent.
You should pick the isoparm (the visible line in the surface) that lines up with the curve you have already selected. Alias will then display a locator tool at the point of tangency.
Use the arcs in the locator to adjust the angle of the curve at the point of tangency. The tangency scale can be adjusted by grabbing the box on the arrow and sliding it up and down the tangency vector. These adjustments can also be made by keying in the amounts in the project tangent options box.
2. Create Square Surface
Once you have the curves aligned to the existing surface, choose Surfaces -> Square -> options. Be sure that rebuild curves are all off, and that the tangency conditions are free. You should not try to force tangency with square surface options. The square surface tools adds isoparms to force tangency. If the surfaces are not aligned by using the project tangent tool on the curves, you should align the surfaces after you create them using tools shown later.
Once you have selected the sections, you should be able to see the surface.
3. Align Tool
If the surface you have built appears satisfactory, you may not need to use this tool at this time. But sometimes, through the course of building and rebuilding surface, you may need to force surfaces to line up. The align tools works well when you have two adjoining surfaces that need to line up. (for aligning more than 2 at a time, there is a tool called "align mesh" that will be shown later.)
Pick Object Edit -> Align -> options
You should pick the edge of the surface you would like to move first. Then pick the edge of the surface that you would like the first surface to move to second. Immediatley after you have made the align, you can change the options in the align window. You can turn curvature off if the join is too drastic. you can switch the alignment from the first surface to the second surface if the join is not satisfactory, and if all else fails, you can do an "undo" by turning tangency and position both to "off".