碇 シンジン

This site has 25 926 accounts created here if you want to count the banned members aswell then it's 30 303
 
And this site has been operating for 3 years so that makes 8642 accounts in a year roughly and 
 
720 members per month
 
166 members a week
 
23 members a day
 
Here is a poll where you can see the genders here not all members have voted but it's something http://mlpforums.com/topic/84789-what-is-your-gender-identity/
 
Here is a poll about age not all members have voted but it's something  http://mlpforums.com/topic/60262-how-old-are-you/

I suppose that you are talking about attachments as pictures.
 
First off press that button near the posting box.
 

 
 
 
 
Then you have arrived in new page this page should contain this button, it may depend on your rank and I don't remember what rank you need to that button to show up.
 

 
Then press the button and choose the image you want to attach into your post.
 
You can also press add to post near the attachment to add a placeholder tag into your post where the attachment shows
 

 
if you don't press add to post it shows like this here: