If want to BUILD a desk & you have zero experience and little money then you better learn to like a crappy desk. If you BUY one that needs to be assemble and you have zero experience then read above.
Check out Habitat for Humanity and your local second hand store like Good Will. You can usually buy a sturdy desk that looks pretty good fairly cheap. You can either paint or stain but not both. That you would even ask about doing both proves you have zero experience. Maybe less. An amateur can paint. It isn't too hard. But don't stain. To stain you first have to sand the desk for 2-3 days Then apply a sanding seal. Let it dry for a few hours. Then sand it all over again. Then apply the stain. Let dry a few hours. Then sand it all over again. Depending on the style and price you pay for stain, you may have to apply several coats. Then sand it all over again. For each coat of stain. Then it is stained and beautiful. Now you have to protect it with polyurethane shellac, or any of another type of protectant. At least 2 or 3 coats. And sand between each coat.
With zero experience you should be finished in about 1 year. And you will have a crappy desk. Trust me kiddo. I have being designing, building, and finishing furniture for over 30 years. Including many desks. I could build a nice, plain desk (with drawers) that you would be proud to have in your home. I have all the room, power tools, lumber, glue, hardware, and 30 years experience. And it would take me about a week to do it right.
Go to Good Will.