A blog normally consist of a main (home or index) page which will display the latest posts, the number of posts displayed which you can set to what ever you want. Refer to setting number of posts to be displayed in main page. In addition to this, you can set the blog to have individual post pages (permalinks). In my honest opinion, you should enable individual post pages as it is one useful feature of blogs. When this is enabled, each post will have its own page plus its own URL. Any visitor to the main page can get to the individual post page of that post by clicking on the post title or by clicking on the timestamp . Most will not even know that that is a permalink on which you can click to get to that individual post page, but you can do some modification to the template to make it display like so that there is a better chance that a visitor will know what that is. If you want to do that, refer to Make permalink more prominent.
Some visitors (or maybe even you yourself) may want to link to a particular post, and you want the URL of that individual post page. There are many ways to do that. One is to right-click on the timestamp and select "Copy link location" (this is for FireFox. For Internet Explorer, it is "copy shortcut"):
This will copy the URL into clipboard and you can paste that into wherever you like, for example when making a hyperlink to the post, etc. You can also click on the timestamp and be taken to the individual post page and copy the URL direct from the address bar at the top of the browser.
Then, to make a clickable link (hyperlink) you got to type the HTML for a hyperlink like the example below:
<a href="URL of individual post page">Title of post</a>