definitely finish it off with something protective.
the most typical next step would be to use polyurethane. pretty straightforward to use.
decide on if you want satin, semi, or gloss finish and brush it on, even and smooth.
in my experience, it usually takes 3-4 coats with light sanding in betwen each coat. Make sure to allow proper time for drying between each coat.
I know Minwax makes a good product and I'm sure there are others.
GL with your project.
Post pics when it's done.