ID NAME
Id name you can see in your steam control panel, click edit my SteamID and there you will see: Custom URL: http://steamcommunity.com/id/iid name (if you didn't set it up, they get profile number or steam id). Just copy id name and paste it into fill in form.

17 DIGIT PROFILE NUMBER
You can see 17 digit profile number in the main adress bar, just copy it and paste into fill in form.

STEAM ID
You can find out your steam id in several different ways. We will mention 2.

#1 While you are in-game on some Team Fortress 2 server, open the console using the ~ key and type status in the console. It will show you your steam id number, for example 0:0:0000.

#2 Go in your steam directory - thats where your game is installed, usually C:\Program Files\Steam, find file named steam.log and open it with notepad. Search for lines (you can use ctrl + f command to find it faster): Found existing connection x.xxx.xxx.xxx.xx:xxxxx for 0:0:0000. The last numbers are your steam id.

Copy your steam id number and paste into fill in form.