Router Software

router to tftp server software copy

I want to copy new software from tftp server to my router and i tried many times but its failed so any one know the way to do that Software/Hardware used: software

change router software version

i want to change my router software version but i do not know what to do after download the software from cisco website to my pc I how I will copy the software from my pc to the router?? Software/Hardware used: software