Where in the world is this project? I'll assume this is a somewhat remote Third World location. Even in the most remote locations, materials as simple as wax or paint may be of use (if reapplied regularly). Also given the resources, creating your own varnishes may be feasible.
As for steps there are many sources. I'll simply outline them here:
1) prepare the surfaces - removing all tool marks, bumps, etc. leaving the surface smooth to the touch.
2) alter the color (if desired) - in remote areas, there will be craft traditions familiar with locally accessible materials (like people who dye cloth). Where I live, walnut husks can be cooked to make a great stain for wood called Vandyke brown. I'm sure there is some source near you; commercial or craft-based that will work.
3) coat with a protective layer - oil, wax, varnish, etc. are applied to resist water and other elements. This step usually is repeated: add a coat, perhaps apply sand or steel wool to smooth, add a coat, and so on, until desired result is achieved.
Steps 2 and 3 can be combined if you are using paint or a product that both colors and protects at the same time.
My suggestion is to look to local boat-builders and follow their lead. The finishes used in wooden boat building will have the characteristics you are looking for (given your comments about moisture) and the boat-builders will know how to apply the finishes they use.
Books like the following may be useful (depending on your location):
Natural Dyes and Home Dyeing
Understanding Wood Finishing: How to Select and Apply the Right Finish