There is two simple ways I would go about it.
1) Go to a store that sells stains. If they have that I am sure they will also have wood filler. Get the one that would match the wood color. Some also simply go by 'oak' wood color, something like that. If you used a stain then your in luck! These are usually stain-able.
2) Make your own. Very simple and I have been doing this more lately. If you have a sander and the same wood (assuming you made this). Or just get a little of that wood. Anyway using a sander just sand away. When you have a good amount of sand dust collected but it in a little dish. Add some wood clue and mix till you get a nice paste. Just like that you would have made your own simple wood filler. The only thing is I am not sure this is stain-able. It could be since there is wood in it, but it could simply not stain well in that spot. Something to test on.