There are many vi tutorials online and I recommend that you do your own search to find something more complete. And of course use vimtutor on your Slackware box.
But I have recommended Vim as a good choice for you, so I want to be as helpful and encouraging as possible to get you introduced to it as painlessly as possible. To that end I hope that you will find the following notes helpful - they assume that you have not previously used Vim so I hope they are not too simplistic.
First, make sure that you are using Vim!
There are several common Vi clones, and on most Linux systems when you invoke vi you are actually running something else.
On a clean Slackware installation vi is actually a symlink to elvis, another vi clone. Elvis is a fine vi replacement, but it has enough differences from Vim that the first thing I do when installing Slackware is change the symlink to point to Vim instead. As root...
ln -s vim vi
You could also simply invoke it as vim, of course. But if you are going to learn and use vi(m) changing the symlink is worthwhile.
Next, get oriented quickly!
I think the most difficult thing for people who simply open vi or a clone is that they see the blank page and begin typing - and weird stuff happens! Then they can't get out of it and they leave in frustration thinking the learning curve is too steep!
So to get past that point as quickly as possible note the following:
1. Vi(m) has two modes - command mode
and insert mode
(also called normal mode and edit mode respectively).
2. When you first start vi it is always in command mode, so key presses are interpreted as commands, not text.
3. To enter insert mode from command mode simply press i
, then begin typing your text.
4. To return to command mode at any time simply press the ESC
You will see helpful status messages in the lower left corner of the terminal window as you change modes.
To leave vi you must be in command mode (pres ESC if not sure) then try one of these:
ZZ (shift-zz) - writes (saves) the current edits and exits.
:wq - writes (saves) the current edits and quits (same as ZZ).
:q - quit, prompts you to save any unsaved edits first (:w will write the to file)
:q! - quits without saving edits.
Now use it as simply as any plain text editor!
Open a new play file to edit...
Enter insert mode...
Type a few lines as with any other editor. ENTER for line breaks, BKSP and arrows for moving around, most everything will work just as you expect it to.
Return to command mode, save and exit...
To modify your new file simply open it again, return to insert mode, change and exit.
Now what is difficult about that? If you learned no other commands this will allow you to use it as the proverbial "plain text" editor... but of course, you really want to do a little more than that so now the way is open for you!
Now that you know the way in and out, and how to toggle between command mode and insert mode, use vimtutor to learn a few more keystrokes and expand your horizons.
Granted there are MANY more things that you can learn - that is what makes it so powerful! On the other hand, you only need to learn the things that you need to use, so the learning curve is only as steep as your intended usage!
A few quick and useful commands (in command mode of course...)
/something - Search for "something" forward in the document. ENTER to move to the first occurance.
/ENTER - Repeat previous search, move to next occurance.
?something - Search backward...
?ENTER - Repeat previous search backward, move to previous occurance
(Searches are actually full regular expression matches)
dd - Delete the current line
x - delete the current character
yy - Yank (copy) the current line
p - paste the last yanked line at the current position
Learn what you need and don't feel as if you need to learn it all just to get started! I think it will grow on you!