Requirements for a live guitar performance?

I need to perform a live guitar with my band members(4 including me) at my school's farewell day. Although There are speakers over there I don't believe in them. No one knows when it works and when it doesn't. Thus i'm planning make all arrangements for my live performance at my school from my pocket. As a self taught guitarist i don't know any thing with respect to sound. Our band owns a Simple elec. guitar, Gnx 3000, a elec. b, a keyboard. All necessary arrangements hav to be made by me. Hence for an audience within an area of 60ft by 60ft square what things i need to hav. and please explain me the things to be bought and its settings.