Inspiration vs. Stealing

I've read several blog posts where people have created things and then someone else stole it and started selling it. It makes me really nervous about posting things that I've created. Not because I'm afraid something like this will happen to me but because I don't want anyone to think I've stolen their creations. I find myself inspired by the things I see online and want to try to create my own materials to use in my class. I have issues and don't always like to use what other people have done. It seems that I have this need to tweak it a bit. I have been very inspired by Fran at Kindergarten Crayons. She makes these really cool tiny books to practice sight words. Well I worked on this today and figured out how to do it. I'm really proud of myself for figuring out how to turn the pages around.(If anyone has publisher and wants to know how to flip the text, leave me a comment and I'll be glad to share) So here's my question, what is ethical to post? Would it be ok for me to post this little book that I made? I looked at Fran's and then created one with the sight words that we use. Is it ok if you aren't selling it or if it is based off something that they aren't selling? If you give complete credit to the person who created the original , is it ok? I'm very confused by all this. I don't want someone to think I was stealing. I love this community of blogging teachers and love that you can put your questions and ideas out there for other teachers to use. I have always thought the sign of a good teacher is someone who is willing to teach other teachers and to share what they know. When I was in college, I wrote a honors paper about good teaching practices in reading. There were so many amazing teachers that I observed and the best were the ones that dragged out all their materials to show me and copy for me. I want to be one of those teachers but I want to do it ethically. So some advice is needed.