No matter what you want to do with the console, follow these simple steps to achieve your goal:

1. Open it, by pressing the key right above the TAB-Button
2. Click on you char or whatever you want to change
3. Type in the console command and press enter!

In order to add items, simply type in the following line:

additem "Item_ID" x

(x stands for the quantity of the item)

 

In order to change the value of a skill, use the following command:

setskill x

(Replace "skill" with the skill you want to change. Remember, type every skill in one word, no blanks (e.g. setlongblade, sethandtohand, setstrength). Replace "x" with the value you want the skill to have (e.g. setlongblade 60))

Note: These are just some basic commands, there are many more like activating scripts, adding journal entries etc. For a full list, visit the official TES Forums!