This will depends on which language you're looking for? Please specify which language so other member can suggest the right main fs and cda. Everyone replying is trying to guess what you're after. some thought you want euorpean english, some thought you need thai and some thought you need chinese.
First check out the list of CDA to find the language you want first. this will be the custom pack you need.
Top Sony - CDA W580
Then look through the firmware section for w580. Look for the FS first, then check with the appropriate MAIN. If your FS is Thai, try to look for Thai main first. If Thai main is not available, meaning it isn't available. then use Generic Main. If you're looking for chinese for example: hong kong FS. then you'll need hong kong main. the chinese language is a little more complicated and need a chinese based main.
hope this help