If you are a corporation, you have to go to the top right and select COMPANY PROFILE
On your company profile you will find a little box up there on the left where you can select UPLOAD button to add/update your LOGO
If you are a Travel Management Company, you have to go to the RFP MANAGER
Then go to OPTIONS
Then go to customers
Select the MANAGE button on the right hand side of the customer name
Select CHANGE LOGO
Select your file and upload your LOGO