Search the SCI Studio help for "drawPic". Unfortunately, the online help at bripro.com seems to be gone... in fact, bripro.com seems to gone. Which means SCIStudio can't be downloaded... which means there is no help file available online anymore, and I don't include one in SCI Companion.
Well, hopefully, you have the scistudio help file downloaded already.
There is a kernel function DrawPic (where the help file tells you all the different animations you can use), but you shouldn't use that or the room's picture won't load properly when you save/restore a game. So use the drawPic method on the Rm class (you can specify the animation there too).