To make a app support multiple screen device, you can use put layout here
res/layout/my_layout.xml // layout for normal screen size ("default")
res/layout-small/my_layout.xml // layout for small screen size
res/layout-large/my_layout.xml // layout for large screen size
res/layout-xlarge/my_layout.xml // layout for extra large screen size
and you can set each layout accordingly to device size by selecting preview all option or selecting particular screen