By using the <center> tag. If that doesn't work completely, but does at all, try inputting more of it. It depends on how complicated your lookup is, but <center> should work.
You may...
Flying4you makes custom userlookups if you want something more specific. ------------------------- I agree with the above user, however if you ARE wanting a look-up pre-made. (Already made for you),...
Hover over 'My Account' and a drop down menu will appear. Click 'Edit Profile'. Enter your password, and scroll down to the bottom of the page. There is a box there, put the userlookup code in there....