1) Once you login in to TD you will the following options on the top right
hand side of the screen, they are Back, Next, Tool, Help, Logout (in TD 9.0 i am
saying)

2) Select Help, then you will get various options from that select Add-ins page

3) Then you will get a new window with different Add-ins

4) Select the required add-in , it will automatically install in your system

4) Select an Exce or Word file then you fill find an option Export to Quality
center

5) Select required test cases and upload these by using Export to QC option.