The following easy 6 step are listed below to attach your image. 1st you see how to upload your image to your blogger blog post.
1: Go to your >>> Blogger Dashboard
2: Click >>> New Post
3: Now simply click >>> "insert image" after click new small window are open.
5: after image or upload selected the image and click Add selected button.
Your image is successfully inserted in the Blogger Blog post.
Use image size minimum as you can. And don't attach more than one MB. Don't use JPEG image always use PNG format images, because high resolution image are taking a much time to upload your page. And this is not good for your reader. So always use small & low MB image.