Thank you for the opportunity to help you with your question!

The only method I know is to assume that you have a 100 gram sample, so you have: 
14.3g H, and 85.7gC 

convert these to moles 

14.3g H (1 mol H/1.01g H) = 14.16 
85.7g C (1 mol C/12.01g C) = 7.135 

To find the ratio between atoms, divide all of your components (in this case you only have two) by the lowest number of moles. So 

14.16/7.135 =~ 2 
7.135/7.135 = 1 

Now you know your empirical formula is CH2. You know that the molar mass is 42.00g, so divide this by the molecular weight of CH2 

42/14.03 =~ 3 

Since you know how many times larger the molecular formula is than the empirical, you can multiply your empirical number by three to get the molecular formula, C3H6