Now that you have selected the whole pattern, go to the top left of your screen once again and click on Edit>>Define Pattern
Now go to the picture you would like to put the pattern onto and make a new layer buy going to the top left of your screen clicking Layer>>New>>Layer>>OK
Now that you have done that, you have to use the 'Paint bucket tool'. Once you have selected the paint tool, go to the top right corner this time and you will see a tool bar type thing that says 'Paint bucket Options' In that you will see something that says 'Contents' click the arrow on the drop down and make sure pattern is checked and not foreground.
Now use the Paint bucket to fill the entire picture so that the whole thing is covered in the fill you decided to use.
Now go down to the bottme right half of your page, there should be another tool bar that says layers, channles and paths. Click on the layers tab. There should now be two drop down boxes. In one of them it says normal. Click on the arrow and pick one of the things you can choose from, i picked overlay. Then go to the second drop down andchange the opacity to what you like, mine is at 20.
Now you should have your finished product! mine is in the above preview. See? that wasn't so hard was it? Now you know how to do it so it could come in handy sometimes.
If you have any questions about this tutorial or would like some extra help with it, email Cami at contact.sunny.nights@gmail.com