Thank you for your advice Jeff... I will use that option more now that I know of it... it realy made the file much smaller 
thanks...
@ Pilou
Didn't even know that that is posible, as i said i'm using it only one afternoon and i'm already addicted but will look for tuttorial about it so i don't have to ask stupid questiones...
And one more question... how much does some bether rendering plugin affect my work and should i consider geting one ?
This is my first work in sketchup, it is based on interior design idea for my new room, i like minimalism so the furniture was made acordingly for now just bed a wardrobe and another smaler wardrobe will make the other part also, it took me few hours to make it aldough i had some problems with painting the furniture (ect. edges won't paint themselfes sometimes...)
This is my first work so be kind to comment, and try not to be to strict after all i'm just a noob Sry for the english i'm from croatia
Marin