First you need to download a new firmware on Cisco homepage to that you need a cisco login.

Then you need a tftp server. Klever’s pumpkin is free.

Then we need to take backup of the cisco switch before upgrading.
Login to enable mode.
wr mem
copy running-config tftp://192.168.0.1/config
copy flash:vlan.dat tftp://192.168.0.1/vlan.dat
copy flash:c2950-i6q4l2-mz.121-22.EA6.bin tftp://192.168.0.1/c2950-i6q4l2-mz.121-22.EA6.bin

Then we need to delete old HTML files.
delete /r /f flash:html
Then we need to get the new software on the Cisco router.
archive tar /xtract tftp://192.168.0.1/c2950-i6q4l2-tar.121-22.EA10a.tar flash:

And then you just need to reload the cisco router.
reload