It is true that CO2 can give you better growth than say adding another 1/2 watt per gallon but it can be a double edged sword. You will have worse algae problem with CO2 and medium light if you can't keep the levels steady and constantly over 30ppm. I had the absolute worst BBA and Staghorn algae while using CO2 in my 10 gallon tanks and my plant grew painfully slow. I took it out and added an airstone and my plants have never grown faster.
Obviously if you only have .5 w/g then adding CO2 isn't going to help much because the plants have more than enough CO2 from the air. Also, going from 35ppm CO2 with medium light to 50ppm CO2 with the same lighting will not help as much as adding more light at the same ppm of CO2.
Patience and experimentation to see what works will be your best friend when it comes to plants. Beginner plants under low to medium low light may benefit from CO2 but and airstone will keep levels normal and constant or an HOB will agitate the surface enough that CO2 exchange will be maximized to keep the levels high enough that your plants shouldn't suffer from not injecting it.
And I do also know some that can and do keep plants at high to very high lighting levels and have never injected CO2 while having pristine algae free tanks with no chemicals. Their plants also grow fast, including HC, glosso, pygmy sword, and many other high light plants that are supposed to suffer without CO2 but grow extremely fast.
Be patient with your plants and ask lots of question, read the stickies a couple time and then ask more questions. It can be very frustrating to start out but once you figure out what your plants like live plants make for an ever changing tank and a healthier one.
Sorry Follow It Home if I had made it little too complicated for a beginner. It can be overwhelming but don't let. Just ask your questions and be patient.