How can i make something like this

Greetings everyone, im trying to create an gallery download style but i don’t understand so much, here is the example:

http://imgur.com/WkCGB

There is a theme or plugin capable to do that? i mean, i post something, and it shows as a little thumbnail, so when someone clicks there it opens the post where i put some pictures and download link.

Help is very appreciated, thanks and have a nice day!