If you are taking them off of google, then right click the picture you want and save it to your computer. Then there should be a button in the description of the photo that states, "visit page." Go to the page where the image came from and copy the link. Now to get it onto your blog. Edit the blog you would like to have the picture on and on the side bar with all the tools there should be one that says "picture." When the picture shows up on your blog hit the edit button. There should be an upload button, hit it and find the picture you saved onto your computer. Wait for it to load then there is a spot where you can insert the link that you copied so that you source the picture and do not get in trouble for stealing it.
Hopefully this helps.