First of all, there is already a guide on the Dove of Peace quest (click to view).
Now, as to some of the frequently asked questions on the Medals:
Q1) How do I get a medal?
. A) Medals are awarded for being in the Top 10 lists for Attackers, Defenders, Robbers, and Climbers. There are also medals for being in multiple lists in a single week, and for being in a list for several consecutive weeks. You must be in the Top 10 list at the time the medal is awarded!
Q2) When are the medals awarded?
. A) They are given out at midnight on Monday morning. Only players currently in the lists are given medals; if you were in the list on Tuesday, but pushed out by another player, you will not receive a medal.
(Note: Server time is EST / GMT-5)
Q3) How do I add them to my profile?
. A) When you go to edit your profile, there will be a list of the medals you have earned.
Keep in mind that you must include the brackets for the code to work.
Q4) What types of medals are there?
. A) http://forum.travian.com/showthread.php?t=103725
(1/23/09: Updated link to .com forums, where descriptions are in English.)
Q5) If you know the code for a medal, could you put it into your profile without earning it?
. A) No. Medals must be earned before they will be displayed.