Butan-2-ol has the structural formula:

Using conventional bond notation, you could draw it as, for example:

The only difference between these is a slight rotation of the bond between the centre two carbon atoms. This is shown in the two models below. Look carefully at them - particularly at what has happened to the lone hydrogen atom. In the left-hand model, it is tucked behind the carbon atom. In the right-hand model, it is in the same plane. The change is very slight.

It doesn't matter in the least which of the two arrangements you draw. You could easily invent other ones as well. Choose one of them and get into the habit of drawing 3-dimensional structures that way. My own habit (used elsewhere on this site) is to draw two bonds going back into the paper and one coming out - as in the left-hand diagram above.

Notice that no attempt was made to show the whole molecule in 3-dimensions in the structural formula diagrams. The CH₂CH₃ group was left in a simple form. Keep diagrams simple - trying to show too much detail makes the whole thing amazingly difficult to understand!