Upgrade Image on Cisco Switch\Router

Verify the IOS Version
#show version - this will provide the current IOS Version

Download the latest version from Cisco
Enter the device model number into the search box to the far left of the three columns
The device model is shown with the #show version command from above

Click on the first result in the listing containing "Series"
Find the exact model number in the third column 
Select IOS Software 
Download the IP based ".bin" file

Delete the old image
#delete /f /r flash1:c3750-ipbase-mz.122.35-35.SE5
                          {This is the IOS file name to find it run #show version, its by System image file is}
#delete /f /r flash2:c3750-ipbase-mz.122.35-35.SE5

Copy new IOS to the Cisco device
Start the TFTP service
Use the copy command to transfer the file
# copy tftp flash1
>Address or name of remote host?     ------->TFTP server
>source filename? c3750-ipbasek9-mz-122-55.SE1.bin    ------>Name of file downloaded
>Destination filename? c3750-ipbasek9-mz-122-55.SE1.bin ------>Name of file downloaded (this will be the name used after transfer)

Make sure the file is good
#dir flash1:    {make sure the file name shows up}
#verify /md5 flash1:c3750-ipbasek9-mz-122-55.SE1.bin {verifies the download is not corrupt}

Modify boot path-list
#show boot {lists current config}
#configure terminal
(config)#boot system switch all flash:c3750-ipbasek9-mz-122-55.SE1.bin {change file name to match downloaded file name}

Save & reboot
#write mem
#show version {should have updated IOS}