Gaming@NINA

Hello everyone i was wondering if anyone that has RPG Maker XP knows about when u lay down an object there is white around the edges and when i go into play there black now im a noob at this. I went to the middle layer and tried laying some grass down along the white edges but when i go into test play now there is grass coving over the object which is the tent. so i was wondering if anyone knows how i can fix this problem. And one more question are there anymore objects other than the little set they give u at the begining?. Thanks. Kingassman.

Grass third level
anything else next 2
events well events layer!

The ground level is Layer 1, where the person steps oon etc. Layer 2 is things, the white will go away on Layer 2. Layer 3 is the things you put on the things like Layer 2 has a desk and Layer 3 shoudl have teacups.