755 = everyone can read and execute but only the owner can write to the file. I know you can do it the new way with the letters but I prefer the old school Unix numbers system. the fist digit is for the owner the second is for the group and the third is for everyone else.
4 = can read file.
2 = can write file.
1 = can execute file. (or view contents if it's a directory.)
we want the owner of the file to be able to read, write and execute: 4+2+1=7. we want everyone else to be able to read and execute, but not write to the file: 4+1=5. so we get 755. the most common numbers I use are 755, 777, 644 and 666 (which means anyone can write to the file so it deserves this 'evil' number.)
Glad I could help.
post a thread about your wifi; be sure to include as much info as you can including the output of 'lspci' 'lsusb' 'lsmod' the model of your card and distro.