Insert Images

Hey guys,
I am close to completing my blog layout but for the life of me I cant get images to show up in the “excerpt” part that shows up on my homepage. My blog is https://www.republicaapparel.com/blog. I have tried inserting

<img src=”https://www.vet.cornell.edu/faculty/Sutter/DogSizeVariation.jpg&#8221; alt=”Image” alt=”Image” />

and

<img class=”aligncenter size-thumbnail wp-image-137″ title=”onlyny” src=”https://republicaapparel.com/blog/wp-content/uploads/2010/03/onlyny-150×150.jpg&#8221; alt=”” width=”150″ height=”150″ />

into both the excerpt part and main part of my posts. Although they show up in the main part of the post after I click on the posts, they are not on the homepage.
Thanks