New Background

I have been wanting to make my own background, but never knew how.  I found directions on-line and decided to give it a try.  It took me a lot longer than I thought it would.  I would like to figure out a way to blend the pictures together a little more, but don't have the right photo editing programs to do it.  In highschool I remember using Photoshop and really like it, but...it is a little too expensive to buy:(  Anyone no of anything free online to use?