We're told to wear masks. How do we do it safely and properly?

Thank you, @merpreb That really is an interesting article. It's good to know that CO2 is not a problem.
For those of you who do not want to bother going to the link, here is what the article says:
"There is a myth that if u wear a mask, u breathe your own exhaled CO2. Firstly, the space between your face and the mask is 40-50mm. You breathe and exhale about 500ml of air with each breath. Frankly, the 8-10% air that u may RE-breathe with a mask without an exhale valve actually makes your lungs stronger - like a training mask, as seen in the movie Pink. Doctors actually recommend those masks that RE-circulate CO2 to high performing athletes for improved lung function."
The author is Richa Upadhyay, here are her credentials:
Studied at Makhanlal Chaturvedi National University of Journalism and Communication
Lives in Bengaluru, Karnataka, India
So frankly I am not sure what qualifies her to answer the question, but the answer does make sense. I would prefer to see something by someone who had better qualifications though.
JK

@contentandwell- There's also some common sense here too. If we can inhale O2 why can't we exhale Co2? The CO2 is actually smaller. The masks' holes are much much larger than these molecules. If people are fainting or getting dizzy then maybe there are underlying causes. There are way too many myths that need to stop.

@merpreb Yesterday I wore my mask and went to grocery store and pharmacy it was a total of 2-30 hours This morning I'm still dizzy so I think I'm going to wear a different mask to let that Co2 escape maybe just a silk handkerchief

@jerrynord There are two reasons to wear a mask -
First, as you may have heard, anyone, whether symptomatic or not, can have this virus and spread it through droplets from their nose and mouth to others. Not just through coughing or sneezing, which really spray it to to wider area, but simply by exhaling as well. Wearing the mask as recommended protects others.
Second, when it comes to getting infected, the total amount of virus exposure and where it lands on you are both factors. The corona viruses are known to be able to attach to mucus membranes and the lungs. It is possible to get a virus through your eyes however, they are a much smaller target than the entire respiratory system, and a significant number of droplets would have to get right into your eyes to infect you, so less risk of infection there. I suppose if someone sneezed right into your face there would be heightened risk of transmission through the eyes.
So the key reason behind personal protection (the mask) plus increased social distancing, cleaning frequently touched surfaces, rigorous hand washing, and keeping hands off the face is to limit the amount of the virus that gets into the body and thereby reduce the likelihood of infection.
As a side note, the reason there is such a furor about the lack of adequate personal protective equipment (PPE) for health care providers and other front line personnel is that the TOTAL VIRAL LOAD they face day after day is what is causing so many to become so ill. That is why it is so important to also protect workers like those in the grocery store by keeping a safe distance - to minimize their risk. And why it is important to insist that medical workers be protected with proper attire.
Sue

As a society here in the US we are not used to wear face masks, as many other nations mostly in the Far East have always been doing, when they have an upper respiratory issue, and they want to avoid spreading it to people around.

This Pandemic will teach us for now, and most probably in the future, the need to wear those masks when having symptoms, mostly as a social consideration.

For now, we have to realize that if we want to be able to reduce the risk of the viral spread, and to slowly plan an exit, wearing masks is absolutely necessary.

There are to kind of masks, masks that most people need to wear when in public, to protect others, and medical masks, that are meant to protect those in the frontline that have to protect themselves, and those they treat that might not have the virus.
The Medical providers should of course be in priority for using the Medical protective masks, but in my humble opinion as a care giver to a very vulnerable person, I would include in the group with the need of a Medical masks, also people with chronic health conditions, the elderly, and the most at risk, that while they should practice complete social distancing and staying home, but if they have no choice, and need to go out, medical masks will protect them as well.

Medical masks are masks that are considered N95 or N99, and that means that they can block 95% and more of the virus from getting into the respiratory system. All other masks either purchased or home made, while not completely protecting the person that wears it, is meant to protect people around us, and mainly stops the droplets coming out of our mouth and nose, while talking or coughing, and stops those droplets from getting into the breathing air of people around us.

We should also remember that our eyes, are not covered by the mask, and they are also a port of entry for the virus. Therefore those that need a Medical masks, need some sort of eyes cover like goggles or plastic shields, for more complete protection from others.

@lioness- Are you inhaling through your nose and exhaling through your mouth?

I am glad you pointed out the fact about getting the virus through your eyes. Never hear mention of this in the news. Even the CDC and WHO avoid telling anyone.