Not really sure what you mean. If you've bought or unlocked the skill and you place it in your skill bar, as long as you have enough energy/adrenaline and are not under the effects of a shout prevention hex ([Ulcerous Lungs] [Well Of Silence]) then you should be able to use your command skills.
Maybe im getting the wrong end of the stick, could you elaborate a little bit?
What I mean is that, when I first made a Paragon I put some points also into command. (saw a great build on wiki P/W) When I looked under my skills I dont see any command spells, but yet I can still put some points into command. Is it because I have to be a certain level to start seeing some skills in command?
You have to buy them at a skill trainer first, the will be available in the command line after that.
It cost some gold (1k max) and 1 skill point per skill bought
To answer your next question.. those are chants, shouts, anthems, and echoes. Spells are different. You'll want to learn the difference between each as you get to know your pgon.
Yup just have to purchase the skills, use a tome to get skills already unlocked on your account, or use the hero trainer (which is the cheaper alternative if they have the skill you need)
you need to unlock skills either by purchasing them at a skill trainer (1k and 1 skill point), a hero skill trainer ( 1 hero skill point). Or you can buy tomes and unlock the skill, but that first requires you to unlock the skill with balthazaar faction. Elite skills can be captured from dead bosses using a Capture Signet(1k and 1 skill point). Or also unlocked w an elite tome and balth faction.