Okay. I'll try!
Copy the link that you want to use.
In your post, highlight the word or phrase that you want to hyperlink.
Here, I'll use the phrase 'your post', and the direct link to the above post.
Once it is highlighted by clicking on it and choosing the 'select' option in Mac, or dragging your cursor over it in Windows, then choose the icon of the world with a chain link just at the top of your posting window whilst your chosen word/s are still highlit.
A pop up box will appear. If you have copied the whole link previously, delete the 'http:/' that appears in the box, and then paste your link in that window.
Once you have done that then press the 'OK' or 'Save' button.
Voila - hyperlink is created.
Your post
In geek language the finished product will look like this, WITHOUT the full stops within the 'URL' inside the end brackets:
[U.R.L="http://www.pprune.org/computer-internet-issues-troubleshooting/445817-renaming-hyperlinks-help.html#post6309637"]Your post[/U.R.L]
Hope that helps?