DRAWING ALKANES

Draw our parent chain with the longest carbon chain. In our case, as it has 4 carbons, propane is the longest carbon chain.

Count the carbon chain. This can be from left to right or left to right. Choose whatever you want.

In their assigned position, put the subchains. In our situation, the subchain is methyl and is situated at the propane's second carbon, meaning it will be centered at the propane's second carbon.