According to Google Webmaster's report my site has many crawl errors and all of them are some links with 403 error ! All these links has parameter set_color. Three months ago i went to google webmaster and in parameter handling i set this parameter to ignore. but still i see these errors on google webmaster. Data of indexing of many of these links are in 2011 ! means less than 1 month ago ! I don't know how much these errors efect my SEO and SERP !? and what should i do ?
Also make sure your pages are validated (ie: properly coded). I use Dreamweaver's built-in html validator for my pages; however, you can use any online validator to check your pages - like the one at w3.org
How to make blog as follow? I mean, i my blog is from blog.com, is that necessary for me to make it as follow or that is blog.com's job?
Again, if we report crawl errors for your website, you can use crawl error sources to quickly determine if the cause is from your site or someone else's. You'll have the information you need to contact them to get it fixed, and if needed, you can still put in place redirects on your own site to the appropriate URL. Just sign in to Webmaster Tools and check it out for your verified site. You can help people visiting your site—from anywhere on the web—find what they're looking for.
if you are using this tag in your meta part then remove it to make your blog followed by search engines.