Improve Indexing / Google Performance

[Learning]

I'm not an expert on this subject, but it appears that over 90% of my site has not been indexed by Google. This percentage has remained consistent for about 2 years, which is when I started using Vb6 on the cloud.

When I resubmit the site map, I get 36,034 discovered.

These are the problems, according to Google:

• Crawled - currently not indexed: Google systems - Failed 61,554
• Page with redirect: Website - 203,479
• Alternate page with proper canonical tag: Website - 18,492
• Blocked due to access forbidden (403): Website - 15,669
• Not found (404) ; Website - 67

When I test the URLs with "problems," 99+% pass, yet when I resubmit, the re-evaluations always fail.

I see others have had this indexing issue. Is there a mod that can be done, or a suggestion on improving this performance? How good is vB6 SEO?