It is very easy.
1) Click on your own name in the 'author' colomn at the left. In this way you enter your own profile.
2) At the top you see: Visitor messages | Profile | Statistics | Friends | Contact
3) You enter a new menu. Now click "Number of topics" under the Topics header.
Number of topics : 46 (1.23% of total)
Topics per day : 0.13
Latest topic : Mon Mar 05, 2012 7:21 pm
Find all topics where pomse2001 has posted in
4) Now you can see all the threads which you started once.
@ Mods: Maybe there is a faster method?