Redirecting from .com/ to .com/blog/

Hello,

Using htaccess, I’ve managed to redirect (301) from https://www.altfg.com/index.htm to https://www.altfg.com/blog/

(From https://www.altfg.com/ to https://www.altfg.com/blog/ or vice-versa was impossible. The whole site crashed.)

Since I did that redirect, however, my blog has dropped in the Google toolbar ranking (though the overall # of links has increased).

Google still lists my blog (on search result pages) as https://www.altfg.com. In other words, its bot doesn’t seem to recognize that https://www.altfg.com/blog/ is the actual home/index page.

Does anyone have a redirect code I could use that would be search engine friendly, going from an htm/html page (www.altfg.com/) to a php page (www.altfg.com/blog/)?

(I’m afraid that if I at this stage I go the other around, from “www.altfg.com/blog/” to “www.altfg.com/” the whole site will collapse. Would it?? I’m no php expert.)

Any assistance would be much appreciated.