Click the 'user cp' button near the top of the page, then 'Edit Profile' to get to the signature block which takes HTML code I think, or 'Edit Options' to get to the avatar block that allows you to attach an image under your user name in posts.

As to the comment on useful answers, were you expecting someone to say that there's a secret engine hours timer or wheel revolution counter? I think the best you can do is take the car to a reputable independent and have him/her make an assessment. Enrique in Encino seems to be the go to guy in SoCal. Maybe a Bosch shop can provide an estimate based on the level of wear in the IP. I think you'll be lucky to get an answer in the range of +/- 100K miles without taking the engine apart.

Sixto
95 S420
87 300SDL