This is called the Shift Key, depressing it briefly while typing the first letter of any sentence produces what we call a capital letter. It is also used when using proper nouns like Spain, Robert and Incom Corporation. It is also customary to use it when using the possessive pronoun "I" to refer to oneself.
This is a comma, it's best to think of it as whre a prolonged space between words would be, if you were speaking aloud. As an example, let's use "Caity phoned me today, she says she is doing a lot better now".
Initials can be a tricky matter, the Canadian Prime Minister was William Lyon Mackenzie King, and he can be referred to as either WLM, W. L. M. or W.L.M. But you should always assume that the letters should be upper-case, and depress the Shift Key as mentioned before. Hence "cps" would become "CPs"
Contrary to what Falwell said in his last CNN appearance, the world is not ending tomorrow. You are not running out of time, and you can take the extra half-second it takes to type "you" instead of "u". That extra half-second means the difference between 90% of the Internet dismissing you "some newbie" and "a new player who has joined our game". It's a very worthwhile investment.
Like I said above, except your/ure is only *one* letter difference, so we're talking about possible a quarter of a second. Again, it will take you months to earn the level of introductory respect that you otherwise could have had automatically bestowed with just a few extra keytaps.
Take the time to proofread your message before hitting post. You don't have to use the "Preview" feature, even though we did go to the effort of programming it so that you could. But at least scroll your eyes up your post to see if you have anything blatantly misspelled in a post consisting of a single sentence. "evrything", "recieve" and "wen" would be great examples. More than 10% of your post consists of typos...that makes it rather difficult for us to quickly process in our minds, when we have to try and interpret what "wen" means. When? Went? There are multiple possibilities, and the onus shouldn't be on us to decipher what you mean, if the difference is not the result of foreign languages.