How can i find a guy's steamtrades?

How can i find this guy's steamtrades id?
I did go to steamrep.com to get the numbers id to use with steamtrades.com/user/id but didnt work...
A friend of mine told me this fucker gave him fake feedbakcfraud ( caz he asked him to give me back the game he scammed )Anyway wanna report him on steamtrades and will report him on steamrep too..gonna search my screenshot in the meantime :D
I cant seem to find his damn link with either number from steamrep-.-