Step 1: Insert your image to your Blogspot by clicking "Insert image" icon from Compose or HTML mode. Click on your image, a menu will appear with many options such as: Resize, Allignment, Add caption, Properties and Remove
Step 2: Click "Add caption" and type in the caption for your image. This information will be visible when the image is loaded
Step 3: Click "Properties" and add information for Title text (this text will appear when readers move their mouse over the image) and Alt text (this text will help search engines recognize your image)
Those are 3 simple steps to make your images searchable, especially with google. Enjoy blogging and share this post for other blogger.