Here's what's in the wiki:
warp <mapName> <destination>
Warps Naija to another warp node or the naijastart node of any map. The destination can be either "u", "d", "l", or "r", standing for up, down, left, and right, respectively. Between any two maps (even the same map), warp nodes with opposite directions are paired, provided their mapName parameters point to eachother. Furthermore, whether Naija appears above, below, to the left, or to the right of the target node's rectangle is determined by the destination parameter of the node she entered. If the destination is invalid or absent, Naija will appear at the naijastart node in the specified map. If there are multiple valid targets, the one closest to Naija appears to be chosen.
As an example, in map1, there are three nodes: "warp map2 u" (1), "warp map1 l" (2), and "warp map1 r" (3). In map2, there is one node: "warp map1 d" (4). If Naija enters node (1) from any angle, she will appear at the top of node (4)'s rectangle. If she enters node (4) from any angle, she will appear at the bottom of node (1)'s rectangle. Similarly, node (2) will lead her to the left of node (3), and node (3) will lead her to the right of node (2).
N, S, O (or E), and W don't seem to do anything for me, though. If there's anything confusing there, let me know, and I'll try to reword it.