At this point you are ready to start sending.
First get the key adjusted right (right for you).
Smooth up and down motion with no side play in the pivots.
Enogh gap so the contacts don't accidentally hit each other.
Enough spring tension so you don't have to lift the knob up yourself, but can let it return on its own, but not so much tension that you will tire yourself out fighting it.

Next, you have a few decisions to make:
Do you start sending with the same hand you use to write, or the other one? 

You will develop skill faster if you use your writing hand, but 
will have to drop the key to pick up a pen(cil) to write incoming text (after a while, it will be to just take notes)
For what its worth, I made that choice and am stuck holding a pencil while keying, or dropping the pencil to grab the key on every "over". I think most people make this choice. If you insist on keyboarding everything, and are a ten finger typist, it makes no difference.

The second choice is where to place the key. Either it goes at the leading edge of the table, or toward the back. If it is at the front of the table, your your arm is floating free when you send, with perhaps only the heel of your hand (below your little finger) on the table for stability. If the key is toward the back of the table, your forearm just ahead of the elbow rests on the table. 
The decision comes down to what feels most natural to you.

The next step is to develop some muscle skills. 

LIGHTLY hold the knob of the key. Thumb on one side, one or two fingers on top, one finger on the opposite side.  Any leftover  finger(s) can wave in the air, or rest on the base of the key.
Don't let go of the key. Don't slap the key. Don't tap the key. 

Listen to a string of machine made dits from the file "MACHINE SENT DITS .mp3" and try to "play along". Every time you send a dit the key should come all the way back to the point where the spacing adjustment bolt hits the stop. Expect to take a few tries to get in sync, but you should be able to get dialed in after a while.

Once you have that under control, try it with dahs.

If you have a program like "Audacity" or something else that lets you record and examine the waveform of your sending, look for an even one to one on-off ratio. Compare it with the machine sent spacing. They should at least resemble each other. Look for consistency and a 3:1 on-off ratio for dahs.
If you can't look at the waveform, just try and make your sending sound like the machine.

Once you have that under control, try "MACHINE SENT DIDAH.mp3"

Practice these frequently as warm up exercises. Keep refering to the machine sent files, to ensure that when you think you are sending didah, you aren't sending didiit. 

Write down some text that uses letters you already know and send that. Send to someone who already knows Morse and see what they think you sent.

If you have a code reader, or software like CW GET, try sending to that. Don't be disappointed if it doesn't understand you.

Now back to receive practice. 
To avoid the ever lengthening file names, the files will be called
"WEEK 3 and ....mp3 

This weeks characters are :
G 5 / Q 9 Z H 

The files sent on air are in the folder "EXTRA PRACTICE"


Once you are tired of receiving and want to try sending again, try sending along with the practice files. Try to make your Morse sound like what you hear in the practice files.
Play the individual letter files, repeating in a loop, and try to imitate them. Each individual letter file has a about a second on before and after the letter, so there is time to practice sending  that letter in that "quiet" time. If you can, try recording yourself and comparing your sending to machine sending.