external 16gb flash

hello all, 1st post so be gentle!
i have a fusion5 tablet running android 4 ics. not the best tablet in the world but functional, i have bought a 16gb micro tf card and installed it in the side of the tablet
the system see's the storage fine, i can copy and paste to it from any file on the tablet ok so i know the card is in working order, the thing is i have a wifi transfer prog which
i use to move files from my pc to the tablet, now i can move any file to the internal storage but when i direct it straight to the 16gb micro card on extsd1 it doesnt want to play
it says the directory is not writeable which is a pain in the backside, i know it works and the tablet works but i dont know my way around an android system at all, i have read something about permissions and root ?
as i said earlier i am a newbie when it come to android, is there a free app i can use to overcome this?
hope someone can help.
thanks for looking anyway