How To Change Read More Text With Your Image In Blogspot

1.Click 'Design' > 'Edit html' for your blog.
(Tick the 'Expand widget templates' box)

2.Find this Code :
<data:post.jumpText/>

3.Now just choose the image you want to use below and Replace Read More with the code provided for the image.And replace it <data:post.jumpText/> to image code.

Images you can use for your read more:-

Image Preview :

<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9I_vNsGkYpjcwJdVuHHp0ioiUDKOfMhlzercGui69upj76nttpKmFnlrA-7sI0rAOHuLVwyOx83kTY7H8MjPfAwScZwR5Erc0MQ7voCrOuz5CkCB1jn9Pu3R1_emoX2HmwBKK24XyhCP2/s1600/read-more-4.png" border="0" alt="Read Full Post" />

You Can Change Your Picture By Changing Yellow URL.
Some Gif,Png,Animated Button Are Also Available Here
http://exeideas.blogspot.com/2011/07/new-collection-of-read-more-button-with.html