I would suggest start by filling the individual requests that you see where people start their own thread looking for things. Then once you are super comfortable and want to do more...start your own thread, but be warned you will probably get a TON of requests and occasionally you might be overwhelmed. We have lost a lot of GREAT DISigners that way.
You can not post pictures directly to a post. Here is what you can do to show off the great items that you make:
Get a free photobucket account at
www.photobucket.com.
Then upload your pictures to there.
Once they are uploaded point your mouse at the picture and you will see a drop down list below the picture.
Then left click your mouse on the words "IMG Code". When you do this you will see the word "copy" show up where the code was.
Now go back to your post on the DISBoards and right click and "paste" the code into your post and the picture will show up once you complete the post.
Another option is to get a 4shared account. Which ever you decide, you can post a link to your shared things in your signature like I do in mine below.