put site in secure folder in shared linux server.
This was your mistake, I think. If you're using Plesk or some other CP, there will be an option, "house all secure content in a single directory." You want this option off. This will make life a lot easier. This way, all pages and objects can be served from the same location, over https or http.
The second thing you should do is learn to use relative paths. Instead of
<img src="http: // example.com/images/logo.jpg">
do this
<img src="/images/logo.jpg">
The leading slash is important. Consider
index.html
products/index.html
products/widgets/index.html
products/widgets/green/index.html
width dot slash syntax, you have this nightmare
src="images/logo.jpg"
src="../images/logo.jpg"
src="../../images/logo.jpg"
src="../../../images/logo.jpg"
Using the leading slash will always start from the domain root and you have one path for all pages:
src="/images/logo.jpg"
How this relates to security warnings: Doesn't matter whether it's http or https, this approach will request the resource over the appropriate protocol.
Last, once you correct the secure directory issue, if you're still getting warnings, right click the page in FireFox and View Page Info. hit the media tab. This will show you where the non-secure items are.
An often overlooked item is the secure/non/secure code in Google Analytics, or a link to the non secure version of install in a Flash object code.