Most guitars have 6 strings. There are some with more than 6 strings, but we will be talking about the 6 string version here.
The strings are numbered from the thinest string, "one", second thinnest, "two", all the way to the fattest string, "six".
On a right handed guitar, it would look like this:
On a left handed guitar it would be the opposite. Another way of thinking about it is, when you are playing the guitar, the bottom string is 1, and the top string is 6
Standard Tuning simply means that the guitar is tuned to Standard Tuning.
On a guitar, Standard Tuning, from the 6th string (thickest) to the 1st string is: E A D G B E
There are many ways to remember it. One way is to make a saying with the letters of the strings.
One of the easiest is: Ed Ate Dynamite Good Bye Ed (EADGBE)
But, of course, what ever method works for you, use it.
When we talk about steps, we mean the number of frets up or down from the current note.
A half step means one fret. So, a half step up, would look like this:
A whole step (or full step) means two frets. So, a whole step up, would look like this:
When we say a Step and a Half, we mean 3 frets up or down.
Two Steps, would be 4 frets up or down.