I think this project is right up your alley:
Also, you can search for "painting cabinets" in the search box at the top of the page for more ideas and similar projects.
Do you mean that they are stained dark and you would like them to look lighter?
If you still want to see the grain, you can go from light to dark but not visa versa. Your best option will involve painting.
Your best option will involve painting. Use a deglosser product to clean the surface ( do not use sand paper, it will damage the surface). I use a water borne urathane primer ( let dry over night). Then I use a water borne urathane finish (I like to use the satin finish). The finish has a 72 hour curing time, It is time consuming, but you will love the finish product.