From user Jtrost:
just substitute "_jtrost_" with "Jtrost"
Wikipedia signature enhancement:
It's quite simple:
1. Create a subpage under your user page (mine is User:_jtrost_/Signature) and on it put whatever you want your signature to be.
2. Click on "my preferences" at the top of any page and in the "user profile" tab insert {{SUBST:your signature's page}}, so mine is {{SUBST:User:_jtrost_/Signature}}
3. Test it out somewhere and fine tune it. Most user's have their own sandbox. For example I have one at User:_jtrost_/Sandbox.