Configuring https on site and in htaccess

I have installed ssl certificates on my server and now I need https on a few sites. 4 pages need forced to https://www.(whatevertheyweregoingtoo) through htaccess and the rest of the site needs to be forced to http://www.(whatevertheyweregoingtoo). Webpages are going to need links and assets changed as well to get this to work. I had the entire site redirecting to https and it worked, but it affected my SEO, so now I switched it back and when I try to get any https the browser seems to loop. If you are interested please contact me.