Alkane nomenclature requires vocabulary that you will use throughout Organic Chemistry.  This includes formal systems ("IUPAC" nomenclature) and names that have a historical origin without necessarily a systematic structural meaning ("common" names).  Often, common names have been adopted by IUPAC as sytematic root names due to ease of describing a structurally complex system.

All organic compounds, alkanes especially, are named using a root name that reflects the number of carbons in the longest carbon chain:

Carbons
 Root name
 Alkane name
1
 meth-
 Methane
2
 eth-
 Ethane
3
 prop-
 Propane
4
 but-
 Butane
5
 pent-
 Pentane
6
 hex-
 Hexane
7
 hept-
 Heptane
8
 oct-
 Octane
9
 non-
 Nonane
10
 dec-
 Decane
These are derived from Greek words, and from pentane up all are related specifically to Greek words for the corresponding number of carbons in the chain.

More complex structures have branched carbon chains.  Naming these is more complex, but straightforward.
  1. Locate the longest contiguous carbon chain and name it--this is the base name of the compound. When there is a choice of two equivalent-length chains to provide the base name, choose the one that has the least number of substituents.
  2. Number the chain starting with the end nearest a substituent.
  3. Name each alkyl substituent based on the number of carbons in it.
  4. List multiple groups in alphabetic order.
Example: 
Unlabeled

The first step is to find the longest carbon chain and count the number of carbons:

Main chain

This is an octane (8 carbons).  Number the chain so that the substituents have the lowest aggregate numbered positions:

Labeled

Designate the substituents, ordering them alphabetically in front of the base name:

4-ethyl-2,3,5,5-tetramethyloctane


The official IUPAC rules are found at https://www.acdlabs.com/iupac/nomenclature/; the direct link for branched hydrocarbons is https://www.acdlabs.com/iupac/nomenclature/79/r79_36.htm.