BHow to use blogs to build links?

I'm not sure what you mean there. Do you want to build links to your blog or do you want to build links to your product site using your blogspot blog?

If it is the building links to your blog, then here are a couple of tips:

1. Article marketing

Write and submit articles with a link back to your blog. There are many guide out there which help you with this. Search Google for "bum marketing" or even better, search this forum.

2. Content marketing

Market your content. Vote it in social media sites. Get help from your friends to vote it up. Go to blog and start posting useful comments. Introduce yourself to niche blog owners and then send them a link to your best blog post.

All these will get your content noticed by people and give them a choice to link back from their blog.

If you want to build links to your product site using your blogspot blog, then create blog posts and link to your site using the basic html code. Add your product site to your blog sidebar.

Hope this helps
Ramkarthik