iPhone doesn't backup or sync into my iTunes

I have an iPhone 5 and when i plug it into my laptop (windows 8) it shows that its charging but it doesn't start backing up or just syncing in general. at first when I plugged it in it wouldn't do anything so i went through some steps on how to update my USB driver cause the USB cord wasn't being recognized and now after I did that (which worked) my phone won't sync at all. when i do plug it in a pop up shows on my phone screen which says "trust or don't trust this computer" and on my laptop screen it asks what to do with this device but the only options are import photos & videos or open file to this device. my phone and itunes are both updated so i don't know what to do.