Welcome to 2Draw! I hope you enjoy your stay. You may also want to try out Oekaki Shi-Painter, which is very good for drawing anime and such. Also be sure to use layers so you don't cover over your black lineart. To use layers in Lascaux, click the "New Layer" button (the white sheet of paper) to create one. Then you can drag it above/under the existing layer. This way, if you color on a lower layer, the colors will go underneath the black lineart. Have fun!