RE: 1/4 Scale Sopwith Baby Paint???
The Olive drab is known as PC-10. There are many many discussions on the exact color of PC-10. FS 34078 is a pretty close match. If its just a fun build I'd go with that.
You can use Model Masters paints. You can also order PC-10 from Warbirdcolors.com. Both types need to be sprayed on.
The Tan color you're asking about is natural linen. Your covering should be close to that color to start with. Solartex has a color thats close. It's really too dark but its not bad for a sport plane.