So to mention anything about hydrocarbons, you first have to find the longest chain of carbons in the molecule! It doesn't have to be straight - it can be bent, or turn in a circle or anything like that! So if you count across this hydrocarbon, you can find the longest chain of carbons is 7! That makes it a heptane.
Next you have to look at the groups - you count in from the nearest side of hydrocarbons. So if you count in from the right side, you can see that there's a methyl group on the third carbon from the right. That makes it a 3-methylheptane! Hope that helps!