All you need to do is once you have that long link address in place, highlight it and type the word or words you want to replace it with. The link remains live but only the words you chose to appear are there.
soarng
Here is how I do it. I'll link one of my posts.
First, you need to have two browsers open, one with the post you're writing, and one with the post you want to link.
Make sure you're in Compose mode.
Okay, let's say I wrote the sentence, Mimi is a big chicken. Highlight the words you want to use for the link. (in bold)
Switch to the other browser, the one with the post you want to link. highlight and copy the URL.
Go back to the post you're writing and click on the little icon with the blue globe on it. A little box will appear in the upper left corner of the screen. Paste the URL in the little box and click okay.
For example,
Mimi is a big chicken.